Method for forming wiring, method for manufacturing thin film transistor and droplet discharging method

ABSTRACT

It is required that a line width of a wiring is prevented from being wider to be miniaturized when the wiring or the like is formed by a dropping method typified by an ink-jetting method. Therefore, the invention provides a method for narrowing (miniaturizing) the line width according to a method different from a conventional method. A region to be liquid-repellent is formed and further, a region to be lyophilic is formed selectively in the region to be liquid-repellent in a surface for forming a pattern, before forming a desired pattern. After that, a pattern for a wiring or the like is formed in the lyophilic region by a dropping method typified by an ink-jetting method for dropping a composition including a conductive material for the wiring or the like.

TECHNICAL FIELD

The present invention relates to a method for forming a wiring and amethod for manufacturing a thin film transistor or semiconductor deviceby dropping a composition including a material of an object to beformed. Specifically, the invention relates to a method for forming awiring and a method for manufacturing a thin film transistor by adroplet discharging method (an ink-jetting method), and further, thedroplet discharging method.

BACKGROUND ART

A droplet discharging method typified by a piezo method or a thermal jetmethod, or a continuous type droplet discharging method attractsattention. These droplet discharging methods have been used for printingwords and drawing images, but they start to be applied to asemiconductor area for forming a minute pattern or the like these days.

A method of forming a film pattern is proposed by Reference 1: themethod makes it possible to improve a method of forming a film patternby an ink-jetting method, make a film thicker, and make a line thinner.Further, problems such as disconnection or short-circuit are not causedin the case of using a conductive film (Reference 1: Japanese PatentLaid Open No. 2003-133691).

According to Reference 1, a substrate is treated in advance so that acontact angle with a droplet is 60 degree, and a droplet is dischargedover a whole area for forming a wiring at a larger interval than adiameter of the droplet attached on the substrate, in a firstdischarging step. A droplet is discharged at a position in the wholearea for forming a wiring in a second discharging step, which isdifferent from the position discharged in the first discharging step, atthe same interval. In a third discharging step, a droplet is dischargedover the whole area for forming a wiring at a smaller interval than theinterval in the first discharging step.

Further, plasma exposure in a normal pressure or in vacuum is cited as asurface treatment for controlling a contact angle. Gases used in theplasma treatment can be selected in consideration of a material of asubstrate surface on which a conductive wiring is to be formed, andtreatment gases such as methane tetrafluoride, perfluorohexane orperfluorodecane can be used, for example, according to Reference 1.

It is required that a line width of a wiring is prevented from beingwider to be miniaturized when the wiring or the like is formed by amethod typified by an ink-jetting method, as described above. Therefore,an object of the invention is to provide a method for narrowing(miniaturizing) a line width according to a method different from themethod described in Reference 1.

Moreover, another object of the invention is to provide a method forforming elements other than a wiring, e.g. a semiconductor film, aninsulating film, a mask, and the like by a method typified by anink-jetting method, and provide a method for narrowing (miniaturizing) aline width thereof.

DISCLOSURE OF INVENTION

In view of the above objects, in accordance with one feature of theinvention, a region to be liquid-repellent is formed on a surface to beprovided with a pattern thereon. Also, in accordance another feature ofthe invention, a region to be lyophilic is formed on a selected regionof a surface and then a droplet of a composition is applied to theselected region for forming a pattern such as a wiring. The compositionmay include a conductive material dissolved or dispersed in a solution.Further, in accordance with another feature of the invention, a regionto be liquid-repellent (liquid-repellent region) is formed and further,a region to be lyophilic (lyophilic region) is formed selectively in theliquid-repellent region in a surface for forming a pattern, beforeforming a desired pattern, according to the present invention. Afterthat, a pattern for a wiring or the like is formed in the lyophilicregion by a method for dropping (dropping method) a composition(including a composition dissolved or dispersed with a conductor in asolution) mixed with a conductive material for a wiring or the like.There is a droplet discharging (ejecting) method (an ink-jetting method)as the method for dropping a composition mixed with a conductivematerial.

A piezo method can be employed as an ink-jetting method. A piezo methodis also used in inkjet printers since it is superior in a dropletcontrollability and has higher degree of freedom in selecting an ink.There are given a MLP (Multi Layer Piezo) type and an MLChip (MultiLayer Ceramic Hyper Integrated Piezo Segments) type as the piezo method.In addition, an ink-jetting method using a so-called thermal method maybe employed depending on a material of a solution, which pushes out thesolution by generating bubbles by heating a heat-generator.

In other words, a liquid-repellent treatment is performed on a surfacefor forming an element, a lyophilic treatment is performed selectivelyon the surface that is exposed to the liquid-repellent treatment, andthen, a wiring or the like is formed by a dropping method on the surfacethat is selectively exposed to the lyophilic treatment, according to theinvention.

Note that a liquid-repellent property is a state that is low inwettability to water, alcohol or oil and other liquids. On the contrary,a lyophilic property is a property of a region that is comparativelyless liquid-repellent than a liquid-repellent region. When a region thatis comparatively low in a liquid-repellent property is formed, a wiringor the like can be formed in the region, thereby narrowing(miniaturizing) a line width accompanying with miniaturization of theregion.

There is a method of performing a plasma treatment on a surface forforming an element as a method of a liquid-repellent treatment. Theplasma treatment is performed under conditions as follows: air, oxygenor nitrogen is used as a treatment gas, the pressure is several tens ofTorr to 1000 Torr (133000 Pa), preferably, 100(13300 Pa) to 1000 Torr(133000 Pa), further preferably, 700 Torr (93100 Pa) to 800 Torr (106400Pa). Namely, pulse voltage is applied in a state of atmospheric pressureor pressure in the neighborhood of atmospheric pressure. At the time,plasma density is 1×10¹⁰ to 1×10¹⁴ m⁻³ to be in a condition of so-calledcorona discharge or glow discharge.

According to the invention, a dielectric is provided between anelectrode used for a plasma treatment and an object (an object to betreated) for the plasma treatment. In other words, the dielectric isexposed to plasma, and contributes to surface modification of a surfacefor forming an element. For example, an electrode provided with adielectric may be prepared and plasma may be generated so that thedielectric is exposed to plasma. Thus, a whole surface of the electrodeis not necessarily covered with the dielectric. As the dielectric,Teflon (a registered trademark) can be employed. When Teflon isemployed, a CF₂ bond is formed on a surface for forming an element andsurface modification is done. Thus, a liquid-repellent property isshown.

When a fluorine-based gas is employed as a treatment gas like Reference1, it is difficult to perform surface modification on a surface of asemiconductor film. This is because a semiconductor film having siliconis removed by the fluorine-based gas. When a fluorine-based gas isemployed, it is also difficult to perform surface modification on asurface of an organic material such as acrylic. This is because thesurface of an organic material is damaged or removed by a fluorine-basedgas.

On the contrary, a plasma treatment is performed using air, oxygen ornitrogen, according to the invention. Therefore, it is possible toperform surface modification on a semiconductor film or an organicmaterial, regardless of materials of a surface for forming an element,which is preferable. Cost is low and an exhaust gas treatment is simplesince a treatment gas is air, oxygen or nitrogen.

In particular, a plasma treatment using oxygen as a treatment gas can beemployed for removing a mask for patterning a semiconductor film or thelike, which is preferable.

In the invention, concrete pulse voltage is resonated to be applied,like each damped oscillation wave, as a damped oscillation waveformperiodic wave in which the damped oscillation wave is generatedrepeatedly and intermittently. For example, a pair of plus pulse andminus pulse is supplied to a primary side of a high-voltage transformerwith repetition frequency, and the damped oscillation waveform periodicwave which is resonated as each damped oscillation wave is outputtedfrom a secondary side of the high-voltage transformer to be applied to apair of electrodes. The voltage rise time of each resonated dampedoscillation wave is preferably 5 μs or less at the time. The repetitionperiod of the damped oscillation wave is preferably 10 to 100 khz. Thepulse is preferably 100 to 10000 pps (10000 times per second).

There is a method for forming a film containing fluorine on a surfacefor forming an element as another method for a liquid-repellentproperty. For example, a film containing Teflon or a silane couplingagent is formed on a surface for forming an element. A film containingTeflon (Teflon film) can be formed by a sputtering method or a CVDmethod. A film containing a silane coupling agent can be formed by aspin-coating method. A film containing fluorine such as Teflon or asilane coupling agent is preferably formed to be a mono molecular layerlevel, i.g. 5 nm or less in thickness. This is because the filmcontaining fluorine is unnecessary in forming a thin film transistor andit is to be easily removed. For example, the film containing fluorinecan be removed by a heat treatment or a patterning treatment.

As a result of the liquid-repellent treatment, surface modification of asurface for forming a conductive film is made.

After that, a lyophilic region is formed selectively. Light irradiationmay be performed to form the lyophilic region. For instance, thelyophilic region is formed by selective irradiation of laser light. Thelaser light preferably has a wavelength that can be absorbed in asurface where the lyophilic region is to be formed. Specifically, when awiring or the like is formed on a glass substrate by a dropping methodtypified by an ink-jetting method, laser light having an ultravioletregion wavelength that is absorbed in the glass substrate where alyophilic region is formed, is preferably used.

As the laser light, laser light oscillated by a gas laser oscillator, asolid laser oscillator, a metal laser oscillator or a semiconductorlaser oscillator can be used. Specifically, an Ar laser, a Kr laser, anexcimer laser (XeCl, XeF, KrF), a CO₂ laser, a YAG laser, a Y₂O₃ laser,a YVO₄ laser, a YLE laser, a YAlO₃ laser, a glass laser, a ruby laser, asapphire laser and the like can be used.

A unit for adjusting a beam shape or a beam course of laser lightemitted from a laser oscillator can be provided between a laseroscillator and an object to be irradiated, that is, a surface forforming an element. For example, a concave lens, a convex lens, a microlens array, a cylindrical lens array or the like can be used as the unitfor adjusting a beam shape of laser light emitted from a laseroscillator. A mirror, a half mirror, other reflectors can be used as theunit for adjusting a beam course of laser light.

A minute lyophilic region can be formed by selective irradiation oflaser light by using an optical pickup element or a fiber.

In addition, laser light is not necessarily specialized in coherentlight produced by a laser oscillator. A lyophilic region can be formedin the same manner as the laser irradiation by light emitted from a UVlamp, a halogen lamp, a flash lamp or the like. A blow treatment forblowing an ozone gas onto a surface for forming an element may beperformed. Corona discharge or glow discharge may be performed on asurface for forming an element.

After that, a wiring is formed by dropping a composition including awiring material onto a lyophilic region by a dropping method.Consequently, a line width becomes narrow and miniaturization can beachieved. Since a composition including a wiring material has highwettability to a lyophilic region, the composition moves to thelyophilic region even when it is dropped on a liquid-repellent regionthat is out of the lyophilic region to some extent. Thus, a wiring canbe miniaturized and more straight. A wiring can be formed in a lyophilicregion, which can prevent a liquid from accumulating (a pool of liquid)after dropping a composition. Therefore, the wiring can be formed withan even width.

According to the invention, a composition (including a compositiondissolved or dispersed with a conductor in a solvent) mixed with aconductor (material for forming a wiring) in a solvent is dischargedsetting) to form a wiring. Specifically, when a wiring is formed by anink-jetting method, a photolithography step such as light-exposure ordevelopment of a mask for patterning the wiring, and an etching step forpatterning the wiring can be omitted.

Such a step of discharging a composition is preferably performed underlow pressure. The solvent of the composition is evaporated until thecomposition lands on an object to be treated since it is discharged, andthus, steps of drying and baking the composition can be both omitted. Itis preferable to perform the step under low pressure, since an oxidefilm or the like is not formed on the surface of the conductivematerial. The step of dropping a composition may be performed in anitrogen atmosphere or an organic gas atmosphere.

At this time, the composition is discharged to be a dot shape (droplet)or a pillar shape by a series of dots; however, they are collectivelyreferred to as a dot (droplet). Discharging a dot (droplet) means that adot-like droplet or a pillar-like droplet is discharged. In other words,since a plurality of dots are discharged continuously, a pillar-like(dot) droplet is discharged in some cases without being recognized as adot.

Gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd),tungsten (W), nickel (Ni), tantalum (Ta), bismuth (Bi), lead (Pb),indium (In), tin (Sn), zinc (Zn), titanium (Ti), aluminum (Al), an alloythereof, a dispersive nanoparticle thereof, or a silver halide particlecan be used as the conductive material. Specifically, silver or copperwhich is low resistant is preferably used. However, in the case of usingcopper, it is necessary that an insulating film containing nitrogen isformed as a barrier film so as to prevent copper from diffusing into asemiconductor film or the like. In addition, ITO (indium tin oxide), IZO(indium zinc oxide) in which zinc oxide (ZnO) of 2% to 20% is mixed intoindium oxide, ITSO in which silicon oxide (SiO₂) of 2% to 20% is mixedinto indium oxide, organic indium, organotin, titanium nitride (TiN), orthe like can be also used as a transparent conductive material.

A lyophilic treatment and dropping a dot can be performed in the sametreatment chamber by using a droplet discharging apparatus (anink-jetting apparatus) in which a droplet discharging unit fordischarging a dot and a unit for light irradiation (light irradiationunit) are provided integrally. Consequently, manufacturing time can beshortened. Further, a unit for a liquid-repellent treatment may beprovided in the same treatment chamber. In addition, a multi-chamberapparatus in which a treatment chamber for a liquid-repellent treatmentand a treatment chamber provided with a droplet discharging unit and alight irradiation unit are provided, may be formed. A multi-chamberapparatus in which a treatment chamber for a liquid-repellent treatment,a treatment chamber for a lyophilic treatment, and a treatment chamberfor discharging a dot are provided, may be used.

One feature of the invention is that a minute wiring is formed by adropping method typified by an ink-jetting method. A structure of a thinfilm transistor for forming a wiring, or the like is not limited. Inother words, a thin film transistor may have either a crystallinesemiconductor film or an amorphous semiconductor film and may be eithera bottom gate type in which a gate electrode is formed under asemiconductor film or a top gate type in which a gate electrode isformed over a semiconductor film.

When a gate electrode, a source electrode, a drain electrode and eachwiring connected to the electrodes of a thin film transistor are formedby a dropping method typified by an ink-jetting method, aliquid-repellent treatment and a selective lyophilic treatment areperformed and then, a dot is dropped onto the region that are exposed tothe treatments, thereby achieving miniaturization.

A method for forming a wiring using a dot having a conductor isdescribed above, but according to the invention, a liquid-repellenttreatment and a selective lyophilic treatment may be performed on asurface for forming a mask or the like, for example. According to theinvention, at least, a surface for forming an element by a droppingmethod typified by an ink-jetting method is liquid-repellent and alyophilic region is selectively formed therein, thereby miniaturizingthe element by a dropping method typified by an ink-jetting method. Asthe elements formed by a dropping method typified by an ink-jettingmethod, electrodes such as a gate electrode, a source electrode a drainelectrode, and a pixel electrode, wirings such as a source wiring, and adrain wiring, a semiconductor film, a mask for patterning asemiconductor film are given.

In other words, a liquid-repellent treatment and a selective lyophilictreatment are performed in the case of employing a dropping methodtypified by an ink-jetting method at least in one step amongmanufacturing steps of forming a thin film transistor. Consequently,miniaturization can be achieved.

According to the invention, a liquid-repellent region can be formed by aplasma treatment using a treatment gas of air, oxygen, or nitrogenwithout materials dependence, in this manner. Thereafter, a lyophilicregion is formed selectively, thereby miniaturizing a wiring or the likeformed by a dropping method typified by an ink-jetting method.Consequently, a liquid-repellent treatment and a selective lyophilictreatment can be performed on every material. Thus, even wirings formedon a substrate or an insulating film can be miniaturized. In addition,miniaturization of a mask or the like to be formed on an organicmaterial can be achieved, since material dependencies are not requiredto be considered.

One feature of the present invention is that a liquid-repellenttreatment and a selective lyophilic treatment are performed on a surfacefor forming an element in one step of forming a pattern of a mask, awiring or the like by a dropping method typified by an ink-jettingmethod. In other words, an advantageous effect of miniaturizing awiring, a mask, or the like formed by a dropping method typified by anink-jetting method after performing the liquid-repellent treatment andthe selective lyophilic treatment in the step described above, can beobtained according to the invention. Therefore, in a step ofmanufacturing a thin film transistor according to the invention, awiring is not necessarily formed by a dropping method typified by anink-jetting method after a liquid-repellent treatment and a selectivelyophilic treatment, and a treatment of the invention may be performedwhen a minute pattern is required to be formed by a dropping methodtypified by an ink-jetting method.

Production-lines of glass substrates from the fifth generation on, ofwhich mother glass substrate is one meter or more in one side, e.g.equal to or more than 1000 mm×1300 mm, 1000 mm×1500 mm, 1800 mm×2200 mm,has been considered. At this time, a large number of panels can beformed from a mother glass, and thus, it is expected that the cost of apanel be lowered. It is possible to build a production line which canmaintain profitability by employing a dropping method typified by anink-jetting method. This is because a photo process can be simplified byforming a wiring or the like by a dropping method typified by anink-jetting method. Consequently, a photo mask becomes unnecessary, andreduction of costs such as a facility investment cost can be achieved.Further, manufacturing time can be shortened since a photolithographystep becomes unnecessary. Efficiency in the use of materials improves,and a cost and an amount of waste liquid can be reduced by a droppingmethod typified by an ink-jetting method. It is preferable that adropping method typified by an ink-jetting method is applied to alarge-size substrate, in this way.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1F are each a cross-sectional view of a thin film transistoraccording to one aspect of the invention;

FIGS. 2A to 2C are each a cross-sectional view of a thin film transistoraccording to one aspect of the invention;

FIGS. 3A to 3F are each a cross-sectional view of a thin film transistoraccording to one aspect of the invention;

FIGS. 4A to 4F are each a cross-sectional of a thin film transistoraccording to one aspect of the invention;

FIGS. 5A to 5F are each a cross-sectional view of a thin film transistoraccording to one aspect of the invention;

FIGS. 6A to 6D are each a cross-sectional view of a thin film transistoraccording to one aspect of the present invention;

FIGS. 7A to 7C are each a cross-sectional view of a thin film transistoraccording to one aspect of the invention;

FIG. 8 is a cross-sectional view showing a liquid crystal display deviceaccording to one aspect of the invention;

FIGS. 9A and 9B are an equivalent circuit diagram and a top view eachshowing a pixel of a light emitting device, respectively, according toone aspect of the invention;

FIG. 10 is a cross-sectional view of a light-emitting device, accordingto one aspect of the invention;

FIG. 11 is a top view of a display device according to one aspect of thepresent invention;

FIG. 12A and 12B are each a cross-sectional view of a display deviceaccording to one aspect of the invention;

FIGS. 13A to 13C show electronic devices according to one aspect of theinvention;

FIGS. 14A to 14D are each a cross-sectional view of a thin filmtransistor according to one aspect of the invention;

FIGS. 15A and 15B each show a plasma unit according to one aspect of theinvention;

FIG. 16 shows a droplet discharging apparatus according to one aspect ofthe invention;

FIG. 17 shows a droplet discharging apparatus according to one aspect ofthe invention;

FIGS. 18A to 18E are each a cross-sectional view of a thin filmtransistor according to one aspect of the invention;

FIGS. 19A and 19B are each a top view of a display device according toone aspect of the invention;

FIG. 20 is a cross-sectional view of a thin film transistor according toone aspect of the invention; and

FIGS. 21A and 21B are each a cross-sectional view of a thin filmtransistor according to one aspect of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment modes of the present invention are hereinafter described withreference to accompanying drawings. The invention can be implementedwith various modes. It is to be understood that various changes andmodifications will be apparent to those skilled in the art, unless suchchanges and modifications depart from the scope of the inventionhereinafter defined. Therefore, the present invention is not limited toEmbodiment modes. Note that the same reference numerals are each givento the same portion or a portion having a similar function throughoutall figures for explaining embodiment modes, and description thereof isnot repeated to be omitted.

An ink-jetting method is used as a dropping method in Embodiment Modeshereinafter. Note that a plasma treatment is used for a liquid-repellenttreatment, and laser irradiation is employed for a lyophilic treatment,unless otherwise noted.

A TFT has three terminals, a gate, a source and a drain, but it isdifficult to precisely distinguish a source terminal (source electrode)from a drain terminal (drain electrode) in a TFT structure. Therefore,one of a source electrode and a drain electrode is referred to as afirst electrode and the other is referred to as a second electrode, indescribing a connection between elements.

Embodiment Mode 1

An example of a method for manufacturing a thin film transistor isdescribed in Embodiment Mode 1.

As shown in FIG. 1A, a substrate 100 having an insulating surface isprepared. For example, a glass substrate such as a barium borosilicateglass or an alumino borosilicate glass, a quartz substrate, a stainlesssubstrate or the like can be used for the substrate 100. In addition, asubstrate made of plastic typified by polyethylene-terephthalate (PET),polyethylene naphthalate (PEN), polyeter sulfone (PES) and a substratemade of synthetic resin having flexibility such as acryl tend to haveworse heat-resistance than other types of substrates. However, suchsubstrates can be used as long as they can resist a treatmenttemperature in a manufacturing step. Specifically, a substrate made offlexible synthetic resin is easy to use when a thin film transistorincluding an amorphous semiconductor film, for which a heat treatmentfor crystallization of a semiconductor film is not required, is formed.

A base film is formed on the substrate 100 as necessary. The base filmis formed in order to prevent an alkaline metal such as Na or analkaline earth metal contained in the substrate 100 from spreading in asemiconductor film and exerting an adverse influence on semiconductorelement characteristics. The base film can be therefore formed by usingan insulating film such as silicon oxide, silicon nitride, siliconoxynitride, titanium oxide, or titanium nitride, which is capable ofsuppressing the spread of an alkaline metal or an alkaline earth metalinto the semiconductor film.

In addition, the base film can be formed by using a conductive film suchas titanium. At this time, the conductive film is oxidized by a heattreatment or the like in a manufacturing step in some cases.Specifically, a material of the base film may employ the one having highadhesiveness with a gate electrode material. For example, a base filmmade of titanium oxide (TiO_(x)) is preferably formed when Ag is usedfor the gate electrode. Note that the base film 101 may have a singlelayer structure or a laminated structure.

A base film is not necessarily provided, as long as it is possible toprevent impurities from diffusing into a semiconductor film. As in thisembodiment mode, when a semiconductor film is formed over a gateelectrode with a gate insulating film therebetween, a base film is notneeded since the gate insulating film can have a function of preventingimpurities from diffusing into the semiconductor film.

In some cases, a base film is preferably provided depending on amaterial of the substrate. It is effective to provide a base film inorder to prevent impurity diffusion in the case of using a substratethat contains a certain amount of an alkaline metal or an alkaline earthmetal, such as a glass substrate, a stainless substrate or a plasticsubstrate. However, a base film is not necessarily provided when using aquartz substrate or the like, for which impurity diffusion does notcause a problem.

After that, a plasma treatment is performed on a surface for forming agate electrode. In this embodiment mode, since the surface for forming agate electrode is a substrate, a plasma treatment is performed on thesubstrate. The plasma treatment is desirably performed without being incontact with a surface for forming a gate electrode.

The plasma treatment is performed by using air, oxygen, or nitrogen as atreatment gas under the pressure of several tens of Torr to 800 Torr(106400 Pa), preferably, 700 Torr (93100 Pa) to 800 Torr (atmosphericpressure or pressure in the neighborhood of atmospheric pressure). Inaddition, an RF source or an AC source can be used as a power supply ofthe plasma treatment. For example, plasma is generated by varying powerby applying voltage with an AC source under conditions of alternatevoltage of 100 V, frequency of 13.56 MHz and the like. Pulse is appliedwith an interval of voltage width of 2 to 4 μsec to discharge stableplasma.

As a result of performing this plasma treatment, surface modification ismade so as to be liquid-repellent, that is, low in wettability, toliquid such as alcohol or oil. In other words, a liquid-repellent regionis formed by a plasma treatment.

As shown in FIG. 1B, a lyophilic region is formed in theliquid-repellent region selectively. In this embodiment mode, a regionin which a gate electrode is to be formed is selectively irradiated withlaser light, thereby making the region in which the gate electrode is tobe formed lyophilic.

A conductive film serving as a gate electrode 103 is formed in thelyophilic region by dropping a dot mixed with a conductor in a solventby an ink-jetting method, as shown in FIG. 1C. In this embodiment mode,a dot in which a conductor of silver (Ag) is dispersed in a solvent oftetradecane is dropped. The gate electrode formed by an ink-jettingmethod can be miniaturized by dropping a dot in the lyophilic regionthat is selectively formed.

After that, when the solvent of the dot is required to remove, a heattreatment for baking or drying is conducted. Specifically, a heattreatment is conducted preferably in an atmosphere containing oxygen ata predetermined temperature, e.g. 200° C. to 300° C. At the time,heating temperature is set in order not to produce unevenness on asurface of the gate electrode. Like this embodiment mode, in the case ofusing a dot having silver (Ag), silver (Ag) that does not include anorganic material can be obtained, since an organic material such asthermosetting resin of an adhesive agent, etc. included in a solvent, orthe like is decomposed, when a heat treatment is performed in anatmosphere containing oxygen or nitrogen. Consequently, planarity of agate electrode surface can be increased and specific resistance valuecan be lowered.

The gate electrode can be made of an element selected from tantalum,tungsten, titanium, molybdenum, aluminum, and copper, or an alloymaterial or a compound material mainly containing the element, inaddition to silver (Ag). The conductive film can be formed by sputteringor plasma CVD instead of an ink-jetting method. A semiconductor filmtypified by a polycrystalline silicon film doped with an impurityelement such as phosphorus or an AgPdCu alloy can be used as theconductive film formed by sputtering or plasma CVD.

As shown in FIG. 1D, an insulating film which serves as a gateinsulating film 104 is formed to cover the gate electrode. Theinsulating film can have a laminated structure or a single layerstructure. An insulator such as silicon oxide, silicon nitride orsilicon oxynitride can be formed as the insulating film by plasma CVD.Note that a dot including a material of an insulating film may bedischarged by an ink-jetting method to form the gate insulating film.Like this embodiment mode, when the gate electrode is made of silver(Ag), it is preferable that a silicon nitride film is used for theinsulating film covering the gate electrode. This is because there is arisk that a surface of the gate electrode becomes uneven, since silveroxide is formed by a reaction with silver (Ag), in the case of using aninsulating film including oxygen.

A semiconductor film 105 is formed over the gate insulating film. Thesemiconductor film can be formed by a plasma CVD method, a sputteringmethod, an ink-jetting method or the like. The semiconductor film is 25to 200 nm thick (preferably, 30 to 60 nm). Silicon germanium as well assilicon can be used for the material of the semiconductor film. In thecase of using silicon germanium, the concentration of germanium ispreferably about 0.01 to 4.5 atomic %. In addition, the semiconductorfilm may be an amorphous semiconductor, a semi-amorphous semiconductorin which crystal grains are dispersed in an amorphous semiconductor or amicro crystal semiconductor in which crystal grains of 0.5 nm to 20 nmcan be seen in an amorphous semiconductor. Note that a state of a microcrystal in which crystal grains of 0.5 nm to 20 nm can be seen isreferred to as a micro crystal (μc).

Semi-amorphous silicon using silicon (also referred to as SAS) as amaterial of a semi-amorphous semiconductor can be obtained by growdischarge decomposition of a silicide gas. As a typical silicide gas,SiH₄ is cited, besides, Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄ and the likecan be used. SAS can be formed easily by a silicide gas diluted withhydrogen, or hydrogen and one or more rare gas elements selected fromhelium, argon, krypton, and neon. The silicide gas is preferably dilutedso that the dilution rate is in the range of 10 times to 1000 times. SAScan be also formed with Si₂H₆ and GeF₄ by a method of diluting them witha helium gas. The reactive formation of a film by grow dischargedecomposition is preferably conducted under low pressure, and thepressure may be about 0.1 Pa to 133 Pa. The power for grow discharge maybe 1 MHz to 120 MHz, preferably, a high frequency power of 13 MHz to 60MHz. The substrate heating temperature is preferably 300° C. or less,and more preferably, substrate heating temperature of 100° C. to 250° C.is recommended.

In this embodiment mode, an amorphous semiconductor film (also, referredto as an amorphous silicon film or amorphous silicon) containing siliconas the main component is formed by using plasma CVD.

A semiconductor film having one conductivity type is formed. Thesemiconductor film having one conductivity type can be formed by using aplasma CVD method, a sputtering method, an ink-jetting method or thelike. When the semiconductor film having one conductivity type isformed, contact resistance of a semiconductor film and an electrodebecomes low, which is preferable. The semiconductor film having oneconductivity type may be formed as necessary. In this embodiment mode, asemiconductor film having N type conductivity 106 is formed by plasmaCVD. When the semiconductor film and the semiconductor film having Ntype conductivity are formed by using plasma CVD, the semiconductor film105, the semiconductor film having N type conductivity 106, and a gateinsulating film are preferably formed sequentially. The sequentialformation is possible by varying a material gas supply without beingexposed to the atmosphere.

As shown in FIG. 1E, the semiconductor film 105 and the semiconductorfilm having N type conductivity 106 are patterned into a desired shape.Although not shown, a mask may be formed at a desired portion and thefilms may be etched by using the mask. The mask is preferably formed byan ink-jetting method, since efficiency in the use of a material can beimproved and a cost and an amount of waste liquid can be reduced.Alternatively, the mask may be formed by a photolithography method. Whenthe mask is formed by an ink-jetting method, further, a photolithographystep can be simplified. In other words, a step of forming a photomask, alight-exposure step and the like are not required, and therefore, afacility investment cost can be reduced and manufacturing time can beshortened. When a mask is formed by an ink-jetting method, a plasmatreatment may be performed on a surface for forming the mask to form aliquid-repellent region, and then, the mask may be formed in theliquid-repellent region. Consequently, the mask formed by an ink-jettingmethod can be miniaturized.

As the mask material, an inorganic material (such as silicon oxide,silicon nitride, silicon oxynitride), a photosensitive ornon-photosensitive organic material (such as polyimide, acryl,polyamide, polyimidamide, polyvinyl alcohol, benzocyclobutene or resist)can be used. For example, when a mask is formed from polyimide by anink-jetting method, polyimide may be discharged at a desired portion byan ink-jetting method and then may be heat-treated at 150° C. to 300° C.to be baked. Thereafter, the semiconductor film 105 and thesemiconductor film having N type conductivity 106 are etched by usingthe mask. A plasma treatment is performed to remove the mask afteretching. Note that the mask formed by an ink-jetting method may serve asan insulting film without being removed.

A plasma treatment may be conducted on a surface for forming a sourceelectrode and a drain electrode. In this embodiment mode, it ispreferable that a plasma treatment is performed on the semiconductorfilm having N type conductivity, which is a surface for forming a sourceelectrode and a drain electrode, and the gate insulating film. Theplasma treatment may be performed without being in contact with thesurface for forming the source electrode and the drain electrode. As aresult of performing this plasma treatment, surface modification is madeso that the surface becomes liquid-repellent, that is, low inwettability, to liquid such as water, alcohol or oil. In other words, aliquid-repellent region is formed by the plasma treatment. As a result,the source and drain wiring can be miniaturized.

As shown in FIG. 1F, a conductive film functioning as a source electrodeand a drain electrode 108 is formed. The conductive film may have asingle layer structure or a laminated structure. As the conductive film,a film made of an element selected from gold, silver, copper, aluminum,titanium, molybdenum, tungsten or silicon or an alloy film using theelement, can be used. Further, the conductive film can be formed by anink-jetting method, a CVD method or a sputtering method. In thisembodiment mode, the conductive film is formed by using a dot includingsilver (Ag) by an ink-jetting method. Specifically, it is performedsimilarly to the case of forming the gate electrode shown in FIG. 1C.Since a dot is dropped in the region treated by a plasma treatment, thesource electrode and the drain electrode formed by an ink-jetting methodcan be miniaturized.

In addition, a lyophilic region may be selectively formed in theliquid-repellent region in the case of miniaturizing the sourceelectrode and the drain electrode as shown in FIGS. 2A to 2C. Forexample, after a plasma treatment is performed on a semiconductor filmhaving N type conductivity that is a surface for forming a sourceelectrode and a drain electrode, and a gate insulating film as shown inFIG. 2A, a lyophilic region is formed by selective irradiation of laserlight as shown in FIG. 2B. After that, as shown in FIG. 2C, a source anddrain electrode 108 is formed by dropping a dot onto the lyophilicregion. Consequently, a line width of the source and drain electrodeformed by an ink-jetting method can be more miniaturized.

As described above, a liquid-repellent treatment by a plasma treatmentor the like is performed, or further, a selective lyophilic treatmentcan be performed in a step of forming an electrode, a wiring or the likethat is required to be miniaturized. Consequently, the electrode, thewiring or the like can be miniaturized.

After dropping a dot for the source and drain electrode, a heattreatment for baking or drying is performed, when the solvent of the dotis required to remove.

After that, the semiconductor film having N type conductivity 106 isetched by using the source and drain electrode as a mask. This isbecause the semiconductor film having N type conductivity prevents thesource electrode and the drain electrode from being short-circuited. Atthe time, the semiconductor film 105 can be also etched to some extentin some cases.

As described above, a thin film transistor in which up to the source anddrain electrode has been provided is formed. The thin film transistor inthis embodiment mode is a so-called bottom gate type thin filmtransistor, in which a gate electrode is formed under a semiconductorfilm. More in detail, it is a so-called channel etch type, in which asemiconductor film is etched to some extent. A substrate where suchplural thin film transistors are formed is referred to as a TFTsubstrate.

As the thin film transistor shown in this embodiment mode, aliquid-repellent treatment and a selective lyophilic treatment areperformed before at least one step of forming a conductive film by anink-jetting method. The liquid-repellent treatment and the selectivelyophilic treatment are performed before forming a gate electrode, asource electrode and a drain electrode by an ink-jetting method, but theliquid-repellent treatment and the selective lyophilic treatment plasmatreatment may be performed before at least one ink-jetting step. Thus,the liquid-repellent treatment and the selective lyophilic treatmentplasma treatment may be performed before an ink-jetting step which isnot shown in this embodiment mode.

According to the invention, a method of miniaturizing a wiring or thelike by performing a liquid-repellent treatment such as a plasmatreatment may be combined. In other words, a step of forming a wiring orthe like by an ink-jetting method after performing a liquid-repellenttreatment and a selective a lyophilic treatment, and a step of forming awiring or the like by an ink-jetting method after performing only aliquid-repellent treatment may be combined.

As described above, a thin film transistor including gate, source anddrain electrodes that are miniaturized by a liquid-repellent treatmentand a selective lyophilic treatment before an ink-jetting step, can beobtained. Further, a wiring can be formed in a lyophilic region evenwhen a dot is discharged out of alignment to some extent. Thus, aposition of a wiring to be formed can be controlled with accuracy.

Efficiency in the use of materials improves, and a cost and an amount ofwaste liquid can be reduced when a wiring, a mask or the like is formedby an ink-jetting method. In particular, steps in the case of forming amask by an ink-jetting method are more simplified than the case of aphotolithography step. Consequently, reduction of costs such as afacility investment cost can be achieved, and manufacturing time can beshortened.

Embodiment Mode 2

A method for manufacturing a thin film transistor which has a structuredifferent from that in Embodiment Mode 1 is described in Embodiment Mode2. The structure different from that in Embodiment Mode 1 is that aprotective film is formed over a semiconductor film. Therefore, othermanufacturing methods may be referred to Embodiment Mode 1 and detaileddescription thereof is omitted.

As shown in FIG. 3A, a plasma treatment is performed on a substrate 100having an insulating surface. A base film may be formed on the substrate100 as necessary. As the result of the plasma treatment, surfacemodification is made so that the surface becomes liquid-repellent, thatis, low in wettability, to liquids such as water, alcohol and oil.Namely, a liquid-repellent region is formed by the plasma treatment.

Thereafter, a lyophilic region is selectively formed in theliquid-repellent region, as shown FIG. 3B. In this embodiment mode, aregion where a gate electrode is to be formed is selectively irradiatedwith laser light, thereby making the region lyophilic.

As shown in FIG. 3C, a gate electrode 103 is formed on the base film, agate insulating film 104 is formed to cover the gate electrode, and asemiconductor film 105 is formed on the gate insulating film. As aresult of performing the liquid-repellent treatment and the selectivelyophilic treatment, the gate electrode formed by an ink-jetting methodcan be miniaturized. After that, a heat treatment for baking or dryingis performed, when the solvent of a dot is required to remove.

Then, a protective film 110 is formed on the semiconductor film. Aninsulating film such as silicon oxide, silicon nitride, or siliconoxynitride is formed as the protective film by an ink-jetting method, aplasma CVD method, a sputtering method or the like. In addition, thesemiconductor film, the protective film, and the gate insulating filmmay be formed sequentially. In the same chamber, they can besequentially formed by changing supply of a material gas without beingexposed to the atmosphere.

In addition, efficiency in the use of materials improves, and a cost andan amount of waste liquid can be reduced when the protective film isformed by an ink-jetting method. And a photolithography step can besimplified when the protective film is formed by an ink-jetting method.Accordingly, a photo mask becomes unnecessary, and reduction of costssuch as a facility investment cost can be achieved. Further,manufacturing time can be shortened, since a photolithography stepbecomes unnecessary. At the time, a plasma treatment may be performed ona surface for forming the protective film to form a liquid-repellentregion, and the protective film may be formed in the liquid-repellentregion. Further, a lyophilic region may be formed selectively in theliquid-repellent region to form the protective film in the lyophilicregion. Accordingly, the protective film formed by an ink-jetting methodcan be miniaturized. A protective film 110 is formed by droppingpolyimide, polyvinyl alcohol or the like by an ink-jetting method inthis embodiment mode.

When the protective film is required to be patterned into a desiredshape, the patterning is conducted by using a mask. At the time, theprotective film can be etched in a self-aligned manner by being exposedto light using the gate electrode as a mask from a backside of thesubstrate. Of course, the mask may be formed by a photolithographymethod or an ink-jetting method. When the mask is formed by anink-jetting method, a plasma treatment may be performed on a surface forforming the mask to form a liquid-repellent region. Further, a lyophilicregion may be formed selectively in the liquid-repellent region.Accordingly, the mask formed by an ink-jetting method can beminiaturized.

As shown in FIG. 3D, a semiconductor film having one conductivity typeis formed. In this embodiment mode, the semiconductor film having N typeconductivity 106 is formed by a plasma CVD method.

As shown in FIG. 3E, the semiconductor film having N type conductivityand the semiconductor film are patterned into a desired shape. In thiscase, although not shown, a mask may be formed at a desired portion andetching may be performed by using the mask. The mask is preferablyformed by an ink-jetting method, since efficiency in the use ofmaterials can be improved and a cost and an amount of waste liquid canbe reduced. However, it may be formed by a photolithography step. Inparticular, steps in the case of forming a mask by an ink-jetting methodis more simplified than the case of a photolithography step.Consequently, reduction of costs such as a facility investment cost canbe achieved, and manufacturing time can be shortened. In this embodimentmode, polyimide, polyvinyl alcohol or the like is dropped as a mask byan ink-jetting method. At the time, a plasma treatment may be performedon a surface for forming a mask to conduct a liquid-repellent treatment.Further, a lyophilic region may be formed selectively in theliquid-repellent region. As a result, the mask formed by an ink-jettingmethod can be miniaturized.

A plasma treatment is conducted to remove the mask after etching. Themask formed by an ink-jetting method may serve as an insulating filmwithout being removed.

A plasma treatment is performed on a surface for forming a sourceelectrode and a drain electrode as in FIG. 1E. In this embodiment mode,a plasma treatment is performed on a semiconductor film having N typeconductivity, which is the surface for forming the source electrode andthe drain electrode, and a gate insulating film. The plasma treatmentmay be performed without being in contact with the surface for formingthe source electrode and the drain electrode. As a result of this plasmatreatment, surface modification is made so that the surface becomesliquid-repellent, that is, low in wettability, to liquid such as water,alcohol or oil. In other words, a liquid-repellent treatment isperformed by a plasma treatment. Thereafter, a lyophilic treatment isperformed selectively on the liquid-repellent region.

As shown in FIG. 3F, a conductive film functioning as a source electrodeand a drain electrode 108 is formed. In this embodiment mode, theconductive film is formed by using a dot including silver (Ag) by anink-jetting method. As the result of the liquid-repellent treatment andthe selective lyophilic treatment, the source electrode and the drainelectrode formed by an ink-jetting method can be miniaturized. Afterthat, a heat treatment for baking or drying may be performed, when thesolvent of the dot is required to remove.

As described above, a thin film transistor in which up to the sourceelectrode and the drain electrode have been provided is formed. The thinfilm transistor in this embodiment mode is a so-called bottom gate typethin film transistor, in which a gate electrode is formed under asemiconductor film. More in detail, it is a so-called channel protectivetype, in which a semiconductor film is not etched. A substrate wheresuch plural thin film transistors are formed is referred to as a TFTsubstrate.

As for the thusly obtained thin film transistor, a liquid-repellenttreatment and a selective lyophilic treatment are performed beforeforming a conductive film by an ink-jetting method. The liquid-repellenttreatment and the selective lyophilic treatment plasma treatment areperformed before forming a gate electrode, and a source and drainelectrode by an ink-jetting method, but the liquid-repellent treatmentand the selective lyophilic treatment may be performed before at leastone ink-jetting step. Thus, a liquid-repellent treatment and a selectivelyophilic treatment plasma treatment may be performed before anink-jetting step that is not shown in this embodiment mode.

As described above, a thin film transistor having miniaturized gate,source and drain electrodes can be obtained by a liquid-repellenttreatment and a selective lyophilic treatment before an ink-jettingstep. Further, a wiring can be formed in a lyophilic region even when adot is discharged out of alignment to some extent. Thus, a position of awiring to be formed can be controlled with accuracy.

Efficiency in the use of materials improves, and a cost and an amount ofwaste liquid can be reduced when a wiring, a mask or the like is formedby an ink-jetting method. In particular, steps in the case of forming amask by an ink-jetting method can be more simplified than the case of aphotolithography step. Consequently, reduction of costs such as afacility investment cost can be achieved, and manufacturing time can beshortened.

Embodiment Mode 3

A method for manufacturing a thin film transistor, which has a structuredifferent from those in Embodiment Modes 1 and 2, is described inEmbodiment Mode 3. The thin film transistor, in which a gate electrodeis provided over a semiconductor film, is a so-called top gate type thinfilm transistor. Therefore, other manufacturing methods may be referredto Embodiment Modes 1 and 2 and detailed description thereof is omitted.

As shown in FIG. 4A, a base film 101 is formed on a substrate 100 havingan insulating surface. After that, a conductive film to be a source anddrain electrode 108 and a semiconductor film having one conductivity areformed sequentially. In this embodiment mode, a semiconductor filmhaving N type conductivity 106 is used for the semiconductor film havingone conductivity. The conductive film to be a source and drain electrodeand the semiconductor film having N type conductivity are formed, andthen, are patterned into a desired shape by using a mask. Although notshown, the mask can be formed by an ink-jetting method or aphotolithography method. Efficiency in the use of materials improves,and a cost and an amount of waste liquid can be reduced when a mask isformed by an ink-jetting method. In particular, steps in the case offorming a mask by an ink-jetting method can be more simplified than thecase of a photolithography step. Consequently, reduction of costs suchas a facility investment cost can be achieved, and manufacturing timecan be shortened. When a mask is formed by an ink-jetting method, aplasma treatment may be performed on a surface for forming the mask toform a liquid-repellent region. Further, a lyophilic region may beformed selectively in the liquid-repellent region. Accordingly, the maskformed by an ink-jetting method can be miniaturized. The mask is formedby dropping polyimide, polyvinyl alcohol or the like by an ink-jettingmethod in this embodiment mode. Thereafter, the mask is baked by heatingas necessary and patterned by dry etching.

A plasma treatment is conducted to remove the mask after patterning. Themask formed by an ink-jetting method may serve as an insulating filmwithout being removed.

As shown in FIG. 4B, a semiconductor film 105 is formed to cover thesemiconductor film having N type conductivity. A mask 112 is formed onthe semiconductor film 105. The mask 112 can be formed by an ink-jettingmethod or a photolithography method. The mask is formed by droppingpolyimide, polyvinyl alcohol or the like by an ink-jetting method inthis embodiment mode. The mask formed by an ink-jetting method is bakedby heating as necessary. Note that a plasma treatment may be performedon the semiconductor film 105 to form a liquid-repellent region at thetime. Further, a lyophilic region may be formed selectively in theliquid-repellent region. Consequently, the mask formed by an ink-jettingmethod can be miniaturized.

After that, the semiconductor film 105 is patterned into a desired shapeby using the mask. At the same time, the semiconductor film having Ntype conductivity can be also patterned. In other words, when thesemiconductor film 105 and the semiconductor film having N typeconductivity 106 have the same etching rate to one gas, they arepatterned simultaneously.

A plasma treatment is performed to remove the mask 112 after patterning.Note that the mask formed by an ink-jetting method may serve as aninsulating film without being removed.

As shown in FIG. 4C, the insulating film which functions as a gateinsulating film 104 is formed to cover the semiconductor film 105. Thegate insulating film may be formed at least between the semiconductorfilm and a gate electrode to be formed later. Then, a plasma treatmentis performed on the gate insulating film 104. As a result of this plasmatreatment, surface modification is made so that the surface becomesliquid-repellent, that is, low in wettability, to liquid such as water,alcohol or oil. In other words, a liquid-repellent treatment isperformed by a plasma treatment.

As shown in FIG. 4D, a lyophilic treatment is conducted by irradiatingselectively on the liquid-repellent region with laser light. In thisembodiment mode, the region to be provided with the gate electrode ismade selectively lyophilic.

As shown in FIG. 4E, a conductive film functioning as a gate electrode103 is formed on the semiconductor film with a gate insulating filmtherebetween. In this embodiment mode, a dot in which a conductivematerial of Ag is dispersed in a solvent of tetradecane is dropped. As aresult of performing the liquid-repellent treatment and the selectivelyophilic treatment, the gate electrode formed by an ink-jetting methodcan be miniaturized. After that, a heat treatment for baking or dryingis conducted when the solvent of the dot is required to remove.

Thus, a thin film transistor in which up to a gate electrode has beenformed and which serves as a semiconductor element is completed. Asubstrate where such plural thin film transistors are formed is referredto as a TFT substrate.

As shown in FIG. 4F, a protective film 113 is formed to at least coverthe gate electrode. The protective film can have a laminated structureor a single layer structure. An insulator such as silicon oxide, siliconnitride or silicon oxynitride can be formed as the protective film byplasma CVD. Note that a dot including a material of an insulating filmmay be discharged by an ink-jetting method to form the protective film.Like this embodiment mode, when the gate electrode is made of silver(Ag), it is preferable that a silicon nitride film is used for theprotective film covering the gate electrode. This is because there is arisk that a surface of the gate electrode becomes uneven, since silveroxide is formed by a reaction with silver (Ag) when a protective filmcontaining oxygen is used.

The thin film transistor in this embodiment mode, in which a gateelectrode is provided over a semiconductor film, is a so-called a topgate type thin film transistor.

As for a thin film transistor formed as in this embodiment, aliquid-repellent treatment and a selective lyophilic treatment areconducted before forming a conductive film by an ink-jetting method. Inthis embodiment mode, the liquid-repellent treatment and the selectivelyophilic treatment are performed before forming the gate electrode byan ink-jetting method. However, the liquid-repellent treatment and theselective lyophilic treatment may be performed before at least oneink-jetting step. Thus, the liquid-repellent treatment and the selectivelyophilic treatment may be conducted before an ink-jetting step that isnot described in this embodiment mode.

As described above, a thin film transistor having a miniaturized gateelectrode an be obtained by the liquid-repellent treatment and theselective lyophilic treatment before an ink-jetting step. Further, awiring can be formed in a lyophilic region even when a dot is dischargedout of alignment to some extent. Thus, a position of a wiring to beformed can be controlled with accuracy.

Efficiency in the used of materials improves, and a cost and an amountof waste liquid can be reduced when a wiring, a mask or the like isformed by an ink-jetting method. In particular, steps in the case offorming a mask by an ink-jetting method can be more simplified than thecase of a photolithography step. Consequently, reduction of costs suchas a facility investment cost be achieved, and manufacturing time can beshortened.

Embodiment Mode 4

A method for manufacturing a thin film transistor, which has a structuredifferent from that of Embodiment Mode 3, is described in EmbodimentMode 4. The structure is different from that of Embodiment Mode 3 inthat a source and drain electrode is formed by an ink-jetting method.Thus, other manufacturing methods may be referred to Embodiment Mode 3and detailed description thereof is omitted.

As shown in FIG. 5A, a base film 101 is formed on a substrate 100 havingan insulating surface. A plasma treatment is performed on the base film101. As a result of this plasma treatment, surface modification is madeso that the surface becomes liquid-repellent, that is, low inwettability, to liquid such as water, alcohol or oil. In other words, aliquid-repellent region is formed by the plasma treatment.

As shown in FIG. 5B, a lyophilic treatment is conducted by irradiatingselectively the liquid-repellent region with laser light. In thisembodiment mode, the region to be provided with the source and drainelectrode is selectively irradiated with laser light to be lyophilic.

As shown in FIG. 5C, a source and drain electrode is formed by anink-jetting method. In this embodiment mode, a dot in which a conductivematerial of Ag is dispersed in a solvent of tetradecane is dropped. As aresult of the liquid-repellent treatment and the selective lyophilictreatment, the source and drain electrode formed by an ink-jettingmethod can be miniaturized. After that, a heat treatment for baking ordrying is conducted when the solvent of the dot is required to remove.

As shown in FIG. 5D, a semiconductor film having one conductivity typeis formed to cover the source and drain electrode. A semiconductor filmhaving N type conductivity 106 is used as the semiconductor film havingone conductivity type in this embodiment mode. The semiconductor filmhaving N type conductivity covering the source and drain electrode isetched for preventing a short-circuit. For example, the semiconductorfilm having N type conductivity between the source electrode and thedrain electrode is etched by a dry-etching method by using a mask.

As shown in FIG. 5E, a semiconductor film 105 is formed to cover thesemiconductor film having N type conductivity. Then, the semiconductorfilm 105 is patterned by using a mask. At the same time, thesemiconductor film having N type conductivity may be also patterned insome cases. In other words, when the semiconductor film 105 and thesemiconductor film having N type conductivity 106 have the same etchingrate to one gas, they are patterned simultaneously. The mask can beformed by an ink-jetting method or a photolithography method. Althoughnot shown, the mask is formed by dropping polyimide, polyvinyl alcoholor the like by an ink-jetting method in this embodiment mode. The maskmay be baked by heating as necessary and patterned by dry etching. Notethat a plasma treatment may be performed on the semiconductor film 105to form a liquid-repellent region at the time. Further, a lyophilicregion may be formed selectively in the liquid-repellent region.Consequently, the mask formed by an ink-jetting method can beminiaturized.

A plasma treatment is performed to remove the mask after patterning.Note that the mask formed by an ink-jetting method may serve as aninsulating film without being removed.

Thereafter, an insulating film functioning as a gate insulating film 104is formed to cover the semiconductor film. A plasma treatment isperformed on the gate insulating film 104. As a result of this plasmatreatment, surface modification is made so that the surface becomesliquid-repellent, that is, low in wettability, to liquid such as water,alcohol or oil. In other words, a liquid-repellent treatment isperformed by the plasma treatment. Thereafter, a lyophilic treatment isperformed selectively on the liquid-repellent region by laserirradiation.

As shown in FIG. 5F, a conductive film functioning as a gate electrode103 is formed on a semiconductor film with a gate insulating filmtherebetween. In this embodiment mode, a dot in which a conductor ofsilver (Ag) is dispersed in a solvent of tetradecane is dropped. As theresult of the liquid-repellent treatment and the selective lyophilictreatment, the gate electrode formed by an ink-jetting method can beminiaturized. After that, a heat treatment for baking or drying isconducted when the solvent of the dot is required to remove.

Thus, a thin film transistor in which up to a gate electrode has beenformed and which serve as a semiconductor element is completed. Asubstrate where such plural thin film transistors are formed is referredto as a TFT substrate.

Then, a protective film 113 is preferably formed to cover at least thegate electrode. The protective film can have a laminated structure or asingle layer structure. As the protective film, an insulator such assilicon oxide, silicon nitride or silicon oxynitride can be formed by aplasma CVD method. Note that a protective film may be formed bydischarging a dot including a material of an insulating film by anink-jetting method. Like this embodiment mode, a silicon nitride film ispreferably used for the protective film covering the gate electrode,when silver (Ag) is used for the gate electrode. This is because thereis a risk that a surface of the gate electrode becomes uneven sincesilver oxide is formed due to a reaction with silver (Ag), when aprotective film containing oxygen is used.

The thin film transistor in this embodiment mode, in which a gateelectrode is provided over a semiconductor film, is a so-called a topgate type thin film transistor.

As for the thusly obtained thin film transistor, a liquid-repellenttreatment and a selective lyophilic treatment are conducted beforeforming a conductive film by an ink-jetting method. The liquid-repellenttreatment and the selective lyophilic treatment are performed beforeforming a gate electrode, and a source electrode and a drain electrodeby an ink-jetting method, but the liquid-repellent treatment and theselective lyophilic treatment may be performed before at least oneink-jetting step. Thus, a liquid-repellent treatment and a selectivelyophilic treatment may be performed before an ink-jetting step that isnot shown in this embodiment mode.

As described above, a thin film transistor having miniaturized source,drain and gate electrodes can be obtained by the liquid-repellenttreatment and the selective lyophilic treatment before an ink-jettingstep. Further, a wiring can be formed in a lyophilic region even when adot is discharged out of alignment to some extent. Thus, a position of awiring to be formed can be controlled with accuracy.

Efficiency in the use of materials improves, and a cost and an amount ofwaste liquid can be reduced when a wiring, a mask or the like is formedby an ink-jetting method. In particular, steps in the case of forming amask by an ink-jetting method are more simplified than the case of aphotolithography step. Consequently, reduction of costs such as afacility investment cost can be achieved, and manufacturing time can beshortened.

Embodiment Mode 5

An example of forming a thin film transistor using a crystallinesemiconductor film is described in Embodiment Mode 5.

As shown in FIG. 18A, a base film 101 is formed on a substrate 100having an insulating surface. The base film 101 may have a laminatedstructure. In this embodiment mode, the base film 101 has a laminatedstructure in which a first base film 101 a and a second base film 101 bare laminated in order. A silicon oxynitride film is formed as the firstbase film 101 a by a plasma CVD method with SiH₄, N₂O, NH₃, or N₂ as amaterial gas, at a pressure of 0.3 Torr (39.9 Pa), an RF power of 50 W,an RF frequency of 60 MHz, a substrate temperature of 400° C. to be from10 nm to 200 nm (preferably, from 50 nm to 200 nm) in thickness. Asilicon oxynitride film is formed as the second base film 101 b by aplasma CVD method with SiH₄ or N₂O as a material gas, at a pressure of0.3 Torr (39.9 Pa), an RF power of 150 W, an RF frequency of 60 MHz, asubstrate temperature of 400° C. to be from 50 nm to 200 nm (preferably,from 150 nm to 200 nm) in thickness.

An amorphous semiconductor film is formed on the base film 101. Theamorphous semiconductor film is 25 to 100 nm thick (preferably, 30 to 60nm). Silicon germanium as well as silicon can be used for the materialof the amorphous semiconductor film. In the case of using silicongermanium, the concentration of germanium is preferably about 0.01 to4.5 atomic %. In addition, the semiconductor film mainly containingsilicon of 66 nm (also, referred to as an amorphous silicon film oramorphous silicon) is used in this embodiment mode.

The amorphous semiconductor film is crystallized to form a crystallinesemiconductor film. A method of adding a metal element promotingcrystallization of an amorphous semiconductor film and heating it can beemployed as the crystallization method. One or more elements selectedfrom Ni, Fe, Co, Pd, Pt, Cu, Au, Ag, In and Sn can be used as the metalelement. It is preferable to use the metal element, since lowtemperature crystallization is possible. However, a step of removing themetal element, a so-called gettering step, is required.

The amorphous semiconductor film may be irradiated with laser light.Continuous wave laser (CW laser) or a pulsed laser (pulse oscillationtype) can be used. One laser or more lasers selected from an Ar laser, aKr laser, an excimer laser, a YAG laser, a Y₂O₃ laser, a YVO₄ laser, aYLF laser, a YAlO₃ laser, a glass laser, a ruby laser, an alexandritelaser, a Ti: sapphire laser, a copper vapor laser, and a gold vaporlaser can be used as the laser.

For example, a Ni solution (including a water solution or an acetic acidmedium) is applied over the amorphous semiconductor film by anapplication method such as spin-coating or dipping or an ink-jettingmethod. At the time, it is preferable to form an oxide film to be 1 to 5nm thick by UV light irradiation in an oxygen atmosphere, a thermaloxidation method, a treatment using ozone water including hydroxylradical or hydrogen peroxide or the like, in order that wettability isimproved in the surface of the amorphous semiconductor film to make thesolution applied over the entire surface of the amorphous semiconductorfilm. In addition, a Ni ion may be injected into an amorphoussemiconductor film by an ion implantation method, a heat treatment maybe performed in an atmosphere of steam containing Ni, or sputtering maybe conducted with Ar plasma using a Ni material as a target. In thisembodiment mode, a water solution including Ni acetate of 10 ppm isapplied by a spin coating method.

After that, the amorphous semiconductor film may be heat-treated for 2to 20 hours at temperatures from 500 to 550° C. and crystallized to forma crystalline semiconductor film. At this time, it is preferable that aheating temperature is changed gradually. Dehydrogenation, which canreduce film unevenness in crystallization, can be conducted, sincehydrogen and the like come out of the amorphous semiconductor film bythe initial heat treatment at low temperature. A magnetic field may beapplied to crystallize with its magnetic energy, or a high powermicrowave may be used. In this embodiment mode, after a heat treatmentis performed for one hour at 500° C., a heat treatment is performed forfour hours at 550° C. in a vertical furnace.

An island like semiconductor film 502 is formed by patterning thecrystalline semiconductor film.

An insulating film serving as a gate insulating film 104 is formed tocover the island like semiconductor film 502. The insulating filmdescribed above can be used for the gate insulating film. TiO₂ is usedfor the gate insulating film in this embodiment mode.

As shown in FIG. 18B, a plasma treatment is performed on a surface forforming the gate electrode. In this embodiment mode, a plasma treatmentis performed on the gate insulating film that is the surface for formingthe gate electrode. The plasma treatment may be performed without beingin contact with the surface for forming the gate electrode. As a resultof this plasma treatment, a surface modification is made so that thesurface becomes liquid-repellent, that is, low in wettability, to liquidsuch as water, alcohol or oil. In other words, a liquid-repellent regionis formed by the plasma treatment.

As shown in FIG. 18C, a lyophilic region is selectively formed in theliquid-repellent region. In this embodiment mode, a region where thegate electrode is formed is selectively irradiated with laser light,thereby making the region lyophilic.

As shown in FIG. 18D, a conductive film functioning as the gateelectrode 103 is formed in the liquid-repellent region by dropping a dotmixed with a conductive material in a solvent by an ink-jetting method.In this embodiment mode, a dot in which a conductor of silver (Ag) isdispersed in a solvent of tetradecane is dropped. The gate electrodeformed by an ink-jetting method can be miniaturized by dropping a dot inthe selectively formed lyophilic region.

After that, a heat treatment for baking or drying is conducted when thesolvent of the dot is required to remove. Specifically, the heattreatment may be at a predetermined temperature, e.g. 200° C. to 300°C., preferably, it may be conducted in an atmosphere containing oxygen.At the time, a heating temperature is set so that unevenness on the gateelectrode surface is not generated. When a dot including silver (Ag) isemployed like this embodiment mode, a heat treatment is conducted in anatmosphere containing oxygen and nitrogen, thereby decomposing anorganic material such as thermosetting resin of an adhesive agent or thelike included in the solvent to obtain silver (Ag) that does not includethe organic material. Consequently, planarity of the gate electrodesurface is increased and specific resistance value can be reduced

The gate electrode can be made of an element selected from tantalum,tungsten, titanium, molybdenum, aluminum, and copper, or an alloymaterial or a compound material mainly containing the element, inaddition to silver (Ag). The conductive film can be formed by asputtering method or a plasma CVD method instead of an ink-jettingmethod. A semiconductor film typified by a polycrystalline silicon filmdoped with an impurity element such as phosphorus or an AgPdCu alloy canbe used as the conductive film formed by sputtering or plasma CVD.

After that, an impurity element is added in a self aligned manner byusing the gate electrode 103. For example, phosphorus (P) is added intoa semiconductor film that is to be an N-channel thin film transistor andboron (B) is added into a semiconductor film that is to be a P-channelthin film transistor.

As described above, a thin film transistor in which up to an impurityregion has been formed, is completed. The thin film transistor in thisembodiment mode is a crystalline thin film transistor having acrystalline semiconductor film and is a top gate thin film transistor,in which a gate electrode is formed over a semiconductor film. Asubstrate where such plural thin film transistors are formed is referredto as a TFT substrate.

After that, as shown in FIG. 18E, an insulating film 507 containingnitrogen is formed to cover the gate electrode 103. In this embodimentmode, the insulating film 507 can be formed by an ink-jetting method,too. After that, dangling bonds of a semiconductor film can be reduced,by heating after forming the insulating film 507.

As for the thusly obtained thin film transistor, a liquid-repellenttreatment and a selective lyophilic treatment are conducted beforeforming a conductive film by an ink-jetting method. The liquid-repellenttreatment and the selective lyophilic treatment are performed beforeforming a gate electrode, and a source and drain electrode by anink-jetting method, but the liquid-repellent treatment and the selectivelyophilic treatment may be performed before at least one ink-jettingstep. Thus, a liquid-repellent treatment and a selective lyophilictreatment may be performed before an ink-jetting step that is not shownin this embodiment mode.

As described above, a thin film transistor having miniaturized source,drain and gate electrodes can be obtained by a liquid-repellenttreatment and a selective lyophilic treatment before an ink-jettingstep. Further, a wiring can be formed in a lyophilic region even when adot is discharged out of alignment to some extent. Thus, a position of awiring to be formed can be controlled with accuracy.

Efficiency in the use of materials improves, and a cost and an amount ofwaste liquid can be reduced when a wiring, a mask or the like is formedby an ink-jetting method. In particular, steps in the case of forming amask by an ink-jetting method can be more simplified than the case of aphotolithography step. Consequently, reduction of costs such as afacility investment cost can be achieved, and manufacturing time can beshortened.

Embodiment Mode 6

An apparatus for a plasma treatment is described in Embodiment Mode 6.

As shown in FIG. 15A, an electrode 403, a dielectric 404 that is formedto cover a surface of the electrode, a power supply 402 connected to theelectrode, a substrate 406 having a surface (an object surface) to beexposed to a plasma treatment, a stage 407 for fixing a substrate areprovided in a treatment chamber 401. Teflon (a registered trademark) isemployed as the dielectric in this embodiment mode. The electrode 403and the power supply 402 collectively correspond to a plasma unit. Inthis embodiment mode, the electrode 403 is used to generate plasma, buta known method may be employed. For example, plasma can be generated bymicrowave or electromagnetic induction.

In this embodiment mode, the dielectric is formed to cover the surfaceof the electrode, but the dielectric may be disposed at least so as tobe exposed to plasma generated between an object to be treated and theelectrode. For example, the dielectric may be provided between theobject and the electrode.

A substrate having a surface to be treated by a plasma treatment isarranged on the stage and pulse voltage is applied from the powersupply. Then, plasma is generated between the electrode and thesubstrate. The density of the plasma is 1×10¹⁰ to 1×10¹⁴ m⁻³. Thepressure in the treatment chamber is several tens of Torr to 800 Torr(106400 Pa), preferably, 700 Torr (93100 Pa) to 800 Torr (atmosphericpressure or pressure in the neighborhood of atmospheric pressure) andpulse voltage is used to discharge. Pulse voltage is applied to generatestable plasma in atmospheric pressure or pressure in the neighborhood ofatmospheric pressure in this embodiment mode. Air, oxygen or nitrogen isused as a treatment gas in this plasma treatment.

Concretely, voltage to be applied is resonated, like each dampedoscillation wave, as a damped oscillation waveform periodic wave inwhich the damped oscillation wave is generated repeatedly andintermittently. A pair of plus pulse and minus pulse is supplied to aprimary side of a high-voltage transformer with repetition frequency,and the damped oscillation waveform periodic wave which is resonated aseach damped oscillation wave is outputted from a secondary side of thehigh-voltage transformer to be applied to a pair of electrodes. Thevoltage rise time of each resonated damped oscillation wave ispreferably 5 μs or less at the time. The repetition period of the dampedoscillation wave is preferably 10 to 100 kHz. The pulse is preferably100 to 10000 pps (10000 times per second).

As the result of the plasma treatment, a surface for forming aconductive film is modified. Specifically, when Teflon is attached tothe surface of the electrode, a CF₂ bond is formed on the surface forforming a conductive film. A specific state of the CF₂ bond before andafter the plasma treatment will be shown in Embodiment. As a result, thetreated surface shows a liquid-repellent property. After that, when awiring or the like is formed thereon, a line width becomes narrow,thereby achieving miniaturization of the wiring.

When a plasma treatment is conducted preferably under atmosphericpressure or pressure in the neighborhood of atmospheric pressure in thismanner, it can be easily conducted without vacuuming. As a result,manufacturing time of a thin film transistor can be shorteneddrastically. Needless to say, the plasma treatment may be performed invacuum.

A treatment chamber having a plasma unit for a plasma treatment and atreatment chamber for an ink-jetting step may be arranged adjacently,thereby making up a so-called multi chamber, which is capable oftransporting a substrate (an object to be treated) having a surface tobe treated without being exposed to the atmosphere. Specifically, amulti chamber is preferable since a substrate having a surface to betreated can be transferred without being exposed to the atmosphere inthe case of conducting a plasma treatment and an ink-jetting step invacuum.

Moreover, it is not necessarily required to perform a plasma treatmentin the treatment chamber since the plasma treatment can be conductedunder atmospheric pressure or pressure in the neighborhood ofatmospheric pressure, as shown in FIG. 15B.

An uniaxial robot 410 for an X-axis and an uniaxial robot 411 for aY-axis are provided in FIG. 15B, and a stage 407 is provided over one ofthe robots. A substrate 406 having a surface to be treated is providedon the stage. The electrode 403 is cylindrical and a dielectric 404covers the circumference of the electrode. Teflon (a registeredtrademark) is employed as the dielectric in this embodiment mode. Otherplasma conditions are described above, and thus, description thereof isomitted.

When the plasma treatment is performed, the electrode and the substrateare relatively moved. When the substrate is larger than the electrode,the electrode and the substrate may be moved relatively. Alternatively,the electrode and the substrate may be moved relatively, while rotatingthe substrate. When they are moved in these ways, a position control maybe conducted with a CCD camera or the like by an alignment marker or thelike as a mark.

The plasma treatment can be easily conducted without vacuuming since theplasma treatment can be conducted in the atmosphere. Consequently,manufacturing time of a thin film transistor can be drasticallyshortened. Of course, the plasma treatment can be performed in vacuum.

Embodiment Mode 7

An ink-jetting apparatus (a droplet discharging apparatus) having alight-irradiation unit is described in Embodiment Mode 7.

As the droplet discharging apparatus shown in FIG. 16, a dropletdischarging nit 701, a light irradiation unit, a stage (a transportstage) 708 for arranging an object to be treated 702, and a CCD camera712 are provided in a treatment chamber 706. A central processing unit715 for controlling a laser oscillator 707, the CCD camera 712, thedroplet discharging unit 701, and the stage 708 is provided. The laseroscillator 707 and a fiber 709 are provided as the light irradiationunit, and a terminal 710 is provided for the end of the fiber. Theterminal includes an optical system, e.g., a lens 711 for converginglaser light. As well as the laser oscillator, an ultraviolet lamp, ahalogen lamp, and a black light can be employed. Light emitted from thelaser oscillator passes through the fiber, is converged to be a desiredsize with the optical lens provided for the terminal, and is emitted onan object to be treated. An optical system comprising a shutter, areflector such as a mirror or a half mirror, a cylindrical lens or aconvex lens, or the like may be installed between the laser oscillatorand the object to be treated so as to adjust a shape or a course oflaser light emitted from the laser oscillator. Such an optical systemmay be provided in the terminal 710.

Light can enter obliquely from above the object to be treated byadjusting the optical system in the light irradiation unit. When theobject to be treated is light-transmitting, light can be emitted frombelow the object to be treated.

Although not shown, a nozzle driving power source and a nozzle heaterfor discharging a droplet are incorporated in the droplet dischargingapparatus, and a moving unit for moving the droplet discharging unit isprovided. When a light irradiation unit having flexibility like thefiber is employed, it can be moved together with being fixed on thedroplet discharging apparatus.

In the droplet discharging apparatus, a substrate that is the object tobe treated 702 is set in the stage 708 having a moving unit in an X-Yaxis direction. The substrate, the droplet discharging unit and thelight irradiation unit are relatively moved to perform a treatment on awhole substrate. In this embodiment mode, the substrate can be moved toan arbitrary point in the X-Y plane by the stage. At the time, positioncontrol is performed by the CCD camera.

In this manner, a lyophilic treatment is performed on the substrate bythe light irradiation unit. After that, a droplet discharging treatmentof dropping a dot onto a lyophilic region is conducted by the dropletdischarging unit.

The lyophilic treatment or the droplet discharging treatment is achievedby relatively moving the droplet discharging unit 701 and the substrate,and a predetermined timing of light irradiation or droplet discharging,thereby drawing a desired pattern on the substrate. Thus, the lyophilictreatment or the droplet discharging treatment can be started when thesubstrate reaches a predetermined position by the stage, where thedroplet discharging unit 701 stands by.

Specifically, since the droplet discharging treatment requires a highaccuracy, it is preferable that the substrate on the transport stage isstopped and only the droplet discharging unit 701 with highcontrollability is scanned when a droplet is discharged. In addition, itis possible that the light irradiation unit and the droplet dischargingunit, and the substrate are moved simultaneously in order to preventdots from being solidified at the start point and the end point of awiring.

The atmosphere of the treatment chamber can be controlled in the dropletdischarging apparatus. For example, a pressure reduction apparatus suchas a cryostat pump can be provided for an exhaust port of the treatmentchamber to vacuum evacuate. A predetermined gas such as nitrogen, argon,or oxygen may be supplied thereinto, and the treatment chamber may becontrolled to be an oxidative atmosphere, a reduction atmosphere or thelike. When the atmosphere is controlled in this manner, the laseroscillator or the like can be arranged outside the treatment chamber andlight irradiation through a window or the like can be performed.

A heater for heating the objected to be treated may be provided in thedroplet discharging apparatus like this. Although not shown, a measuringunit of various physical properties such as temperature or pressure maybe provided as necessary.

The units described above can be collectively controlled by the centralprocessing unit. When the central processing unit is connected to aproduction management system or the like with a LAN cable, a wirelessLAN, an optic fiber or the like, steps can be collectively controlledfrom the outside, which leads to enhance productivity.

A lyophilic treatment and a droplet discharging treatment can beperformed by using the apparatus described above.

FIG. 17 shows an apparatus using an optical pickup element as a lightirradiation unit. It becomes simple and easy to relatively move anobject to be treated, and the light irradiation unit and the dropletdischarging unit by using a light source built-in type light irradiationunit such as an optical pickup element. Consequently, it is possible toenhance position control of light irradiation or control of discharginga droplet.

The treatment chamber 706 can control an atmosphere in the dropletdischarging apparatus like this. For example, a pressure reductionapparatus 721 such as a cryostat pump can be provided for an exhaustport 705 of the treatment chamber to vacuum evacuate. At this time, asubstrate that is an object to be treated is transported into thetreatment chamber from a transport port 703, and fixed on a stage. Apredetermined gas such as nitrogen, argon, or oxygen may be suppliedthereinto from a gas introduction port provided in the treatmentchamber, and the treatment chamber may be controlled to be an oxidativeatmosphere or a reduction atmosphere.

A heater for heating the objected to be treated may be provided in thedroplet discharging apparatus like this. Other structures are identicalto those of FIG. 16, and thus, description in detail thereof is omitted.

In this embodiment mode, a droplet is discharged by a so-called piezosystem using a piezoelectric element; however, a system in which asolution is pushed out by using bubbles generated by heating aheat-generator, a so-called thermal ink-jetting system, may be useddepending on a solution material. In this case, a piezoelectric elementis replaced with a heat-generator. In addition, wettability of asolution with a solution chamber flow path, an extra solution chamber, afluid resistive portion, a chamber for pressurizing, and an outlet for asolution (nozzle, head) is important for discharging a droplet.Therefore, a carbon film, a resin film or the like for adjusting thewettability with a material is formed in each flow path.

The structure of the apparatus makes it possible to perform a lyophilictreatment by light irradiation, discharge continuously a dot in alyophilic region in the same treatment chamber, and form a minute wiringpattern on a substrate efficiently and accurately.

There are a sequential method by which a solution is sequentiallydischarged to form a line-like wiring and an on-demand method by which asolution is discharged in a dot-like as the droplet discharging method.Both methods can be employed.

Embodiment Mode 8

An example of forming a film containing Teflon (Teflon film), instead ofa plasma treatment, is described in Embodiment Mode 8. Othermanufacturing methods are referred to Embodiment Mode 1.

As shown in FIG. 14A, a base film 101 is formed on a substrate 100having an insulating surface. After that, a Teflon film 128 is formed.The Teflon film may be formed to be a mono molecular layer level, i.g. 5nm or less in thickness. The Teflon film can be formed by sputtering,CVD or the like. Thereafter, the Teflon film is selectively irradiatedwith laser light to form a lyophilic region.

As shown in FIG. 14B, a conductive film functioning as a gate electrode103 is formed in the lyophilic region of the Teflon film. The gateelectrode can be formed by dropping a dot including a conductivematerial in a solution by an ink-jetting method. In this embodimentmode, a dot in which a conductor of silver (Ag) is dispersed in asolvent of tetradecane is dropped. As the result of forming the Teflonfilm and forming the lyophilic region selectively there, the gateelectrode formed by an ink-jetting method can be miniaturized.

After that, a heat treatment for baking or drying is conducted when thesolvent of the dot is required to remove. The formed Teflon film of athickness at a mono molecular layer level is removed by the heattreatment.

As shown in FIG. 14C, a gate insulating film 104, a semiconductor film105, and a semiconductor film having N type conductivity 106 are formedsequentially and patterned into a desired shape. After that, aconductive film serving as a source and drain electrode 108 is formed.The Teflon film may be formed before forming the source and drainelectrode. Further, a lyophilic region may be formed selectively in theTeflon film. Consequently, the source and drain electrode formed by anink-jetting method can be miniaturized.

A channel etch type thin film transistor shown in Embodiment Mode 1 isdescribed in this embodiment mode, but a structure of a thin filmtransistor is not limited thereto. In other words, a Teflon film may beformed to have a liquid-repellent property and a lyophilic region may beformed selectively therein, in any one of the methods for manufacturinga thin film transistor described in the embodiment modes describedabove.

As described above, a thin film transistor in which up to a sourceelectrode and a drain electrode have been formed is completed. Asubstrate where such plural thin film transistors are formed is referredto as a TFT substrate.

In addition, as for the thusly obtained thin film transistor, a Teflonfilm is formed and a lyophilic region is selectively formed beforeforming a conductive film by an ink-jetting method. A Teflon film isformed and a lyophilic region is selectively formed before forming agate electrode by an ink-jetting method in this embodiment mode, but theTeflon film may be formed and the lyophilic region may be selectivelyformed before at least one ink-jetting step. Thus, a Teflon film may beformed and a lyophilic region may be selectively formed before anink-jetting step which is not shown in this embodiment mode. A plasmatreatment described above may be performed and further a lyophilicregion may be formed in addition to the steps of forming the Teflon filmand a selective lyophilic region, before employing an ink-jettingmethod.

As described above, a thin film transistor having miniaturized gate,source and drain electrodes can be obtained by the steps of forming aTeflon film and a selective lyophilic region before an ink-jetting step.

Efficiency in the use of materials improves, and a cost and an amount ofwaste liquid can be reduced when a wiring, a mask or the like is formedby an ink-jetting method. In particular, steps in the case of forming amask by an ink-jetting method can be more simplified than the case of aphotolithography step. Consequently, reduction of costs such as afacility investment cost can be achieved, and manufacturing time can beshortened.

Embodiment Mode 9

A case of forming a film containing a silane coupling agent instead of aTeflon film is described in Embodiment Mode 9.

A silane coupling agent is applied by an application method such as aspin-coating method. After that, the silane coupling agent is dried. Inthis embodiment mode, it is dried naturally. Washing is performed so asto remove an unnecessary silane coupling agent. In this embodiment mode,it is washed with water. Consequently, the silane coupling agent can beformed so as to have a film thickness of a mono molecular layer. Afterthat, the silane coupling agent is baked. In this embodiment mode, aheat treatment is performed at 100° C. for ten minutes. In this way, thesilane coupling agent can be formed, and thus, a surface for forming anelement can be liquid-repellent. Note that the silane coupling agent canbe removed. Specifically, the silane coupling agent can be removed by aheat treatment in some cases.

After that, a lyophilic region is formed selectively. A dot is droppedin the lyophilic region. Consequently, a wiring or the like formed by anink-jetting method can be miniaturized.

Other manufacturing methods are similar to those of the embodiment modedescribed above, and thus detailed description thereof is omitted.

As described above, a thin film transistor including miniaturized gate,source and drain electrodes can be obtained by forming a silane couplingagent before an ink-jetting step and selectively forming a lyophilicregion.

Embodiment Mode 10

An interlayer insulating film provided to cover a thin film transistorand a wiring that is formed in an opening portion formed in theinterlayer insulating film are described in Embodiment Mode 10.

As shown in FIG. 6A, a thin film transistor (also referred to as a TFT)120 having a protective film 113 is formed over a substrate 100 havingan insulating surface, according to the embodiment modes describedabove. This embodiment mode describes a TFT as shown in Embodiment Mode1, but any TFT described in the embodiment modes described above may beused.

An interlayer insulating film 121 is formed to cover the TFT 120.Accordingly, planarity can be increased. As the interlayer insulatingfilm, an inorganic material (such as silicon oxide, silicon nitride,silicon oxynitride), a photosensitive or non-photosensitive organicmaterial (polyimide, acryl, polyamide, polyimidamide, benzocyclobutene,or resist), siloxane, or polysilazane and a laminated structure thereofcan be used. Siloxane is formed by using a polymeric material as astarting material, which has a skeleton formed by the bond of silicon(Si) and oxygen (O), and which includes at least hydrogen as asubstituent, or further at least one of fluoride, alkyl group, andaromatic hydrocarbon as the substituent. Polysilazane is formed by usinga liquid material including a polymeric material having a bond ofsilicon (Si) and nitrogen (Ni) as a start material. As an organicmaterial, either positive type photosensitive organic resin or negativephotosensitive organic resin may be used.

When planarity is increased, CMP or the like may be performed on aninterlayer insulating film.

As shown in FIG. 6B, an opening portion 122 having a desired shape isformed at a desired position of the interlayer insulating film 121. Acase of forming the opening portion with a tapered shape in a side facethereof in the interlayer insulating film over the source electrode andthe drain electrode is described in this embodiment mode.

A mask is formed on the interlayer insulating film 121 and the openingportion is formed by etching by using the mask. The mask can be formedby an ink-jetting method or a photolithography method. In particular,steps in the case of forming a mask by an ink-jetting method can be moresimplified than the case of a photolithography step. Therefore,reduction of costs such as a facility investment cost can be achieved,and manufacturing time can be shortened. At the time, a plasma treatmentmay be performed on the interlayer insulating film 121 to form aliquid-repellent region. Further, a lyophilic region may be formedselectively in the liquid-repellent region. Consequently, the maskformed by an ink-jetting method can be miniaturized.

A dot including etchant may be dropped to form an opening portion in theinterlayer insulating film by an ink-jetting method, as shown in FIG.20A. When an opening portion is formed by an ink-jetting method,efficiency in the use of etchant is improved, reduction of a cost, andreduction of waste liquid are possible. And a photolithography step canbe simplified when the opening portion is formed by an ink-jettingmethod.

As shown in FIG. 21A, a material of an interlayer insulating film and amaterial of a wiring may be dropped by an ink-jetting method to form thewiring 123. In this case, surfaces of the interlayer insulating film orthe wiring may be polished by CMP or the like to improve the planarityas shown in FIG. 21B.

A plasma treatment is performed on the interlayer insulating film 121 inwhich the opening portion is formed. As a result of this plasmatreatment, surface modification of the interlayer insulating film andwithin the opening portion (including a side face of the openingportion) is made so as to be liquid-repellent, that is, low inwettability, to liquid such as water, oil or alcohol. In other words, aliquid-repellent treatment is performed by the plasma treatment.Thereafter, a lyophilic region is formed in the liquid-repellent regionby irradiating the opening portion selectively with laser light.

As shown in FIG. 6C, a wiring 123 is formed in the opening portion. Thewiring 123 can be formed by a sputtering method or an ink-jettingmethod. In this embodiment mode, a dot in which a conductor of silver(Ag) is dispersed in a solvent of tetradecane is dropped to form thewiring. At the time, the inside of the opening portion of the interlayerinsulating film (including a side face of the opening portion) islyophilic. The surface of the interlayer insulating film excluding theopening portion is liquid-repellent. Therefore, a dot including amaterial of the wiring can easily enters the inside of the openingportion. Further, the wiring formed by an ink-jetting method can beminiaturized. It is preferable for the case of forming a wiring by anink-jetting method to control a liquid-repellent property and alyophilic property in this manner.

After that, a heat treatment for baking or drying is conducted when thesolvent of the dot is required to remove.

As for the thusly obtained thin film transistor, a liquid-repellenttreatment and a selective lyophilic treatment are performed beforeforming the wiring on the interlayer insulating film by an ink-jettingmethod. In this embodiment mode, the liquid-repellent treatment and theselective lyophilic treatment are performed before or after forming theopening portion, but the liquid-repellent treatment and the selectivelyophilic treatment may be performed before and after forming theopening portion.

When the wiring formed in the opening portion and other wirings (e.g.,signal line) are formed by an ink-jetting method, the wirings can beminiaturized by performing a liquid-repellent treatment and a selectivelyophilic treatment on the interlayer insulating film.

As described above, a thin film transistor having a miniaturized wiringformed on the interlayer insulating film can be obtained by theliquid-repellent treatment and the selective lyophilic treatment beforean ink-jetting step.

Embodiment Mode 11

A method of forming a pixel electrode is shown in Embodiment Mode 11.

As shown in FIG. 7A, a thin film transistor 120 having a protective film113 is formed on a substrate 100 having an insulating surface. Thisembodiment mode describes a TFT as shown in Embodiment Mode 1, but anyTFT described in Embodiment Modes above may be used. A case of forming apixel electrode 125 to be connected to a source electrode and a drainelectrode in a lower portion of the electrodes is described.

After forming a gate insulating film, a semiconductor film and asemiconductor film having N type conductivity are patterned to form thepixel electrode in the area for forming the source electrode or thedrain electrode. The pixel electrode can be formed by a sputteringmethod or an ink-jetting method. The pixel electrode is made of alight-transmitting material or a non-light transmitting material. Forexample, an ITO and the like can be used in the case of alight-transmitting material, whereas a metal film can be used in thecase of a non-light transmitting material. An ITO (indium tin oxide), anIZO (indium zinc oxide) in which zinc oxide (ZnO) of 2% to 20% is mixedinto indium oxide, ITO—SiOx in which silicon oxide (SiO₂) of 2% to 20%is mixed into indium oxide (referred to as ITSO or NITO forconvenience), an organic indium, an organotin, a titanium nitride (TiN),and the like can also be used as specific examples of the pixelelectrode.

Specifically, when the pixel electrode is formed by an ink-jettingmethod, a plasma treatment may be performed on the gate insulating filmwhich is a surface for forming the pixel electrode to form aliquid-repellent region. Further, a lyophilic region may be formedselectively in the liquid-repellent region by laser irradiation.

In FIG. 7A, a dot dispersed with a conductor of ITO is dropped by anink-jetting method to form a pixel electrode. As a result of theliquid-repellent and the selective lyophilic treatment, the pixelelectrode formed by an ink-jetting method can be miniaturized. Afterthat, a heat treatment for baking or drying is conducted when thesolvent of the dot is required to remove.

FIG. 7B shows an example of forming a pixel electrode over a sourceelectrode or a drain electrode, which is different from that of FIG. 7A.The pixel electrode can be formed by a sputtering method or anink-jetting method, as described above. Specifically, when the pixelelectrode is formed by an ink-jetting method, a plasma treatment may beperformed on the source electrode, the drain electrode and the gateinsulating film that are each a surface forming the pixel electrode toform a liquid-repellent region. Further, a lyophilic region may beformed selectively in the liquid-repellent region by laser irradiation.

In FIG. 7B, a dot dispersed with a conductor of ITO is dropped to formthe pixel electrode by an ink-jetting method. As a result of theliquid-repellent treatment and the selective lyophilic treatment, thepixel electrode formed by an ink-jetting method can be miniaturized.After that, a heat treatment for baking or drying is conducted when thesolvent of the dot is required to remove.

In FIG. 7C, an interlayer insulating film 121 is formed and planarized,and then, a wiring 123 is formed and connected to a pixel electrode,which is different from in FIGS. 7A and 7B. The pixel electrode can beformed by a sputtering method or an ink-jetting method, as mentionedabove. Specifically, when the pixel electrode is formed by anink-jetting method, a plasma treatment may be performed on theinterlayer insulating film which is a surface forming the pixelelectrode after forming a wiring 123 to form a liquid-repellent region.Further, a lyophilic region may be formed selectively in theliquid-repellent region by laser irradiation.

In FIG. 7C, an ITSO is employed as the pixel electrode. The ITSO can beformed by dropping a dot dispersed with a conductor of ITO and siliconby an ink-jetting method. Alternatively, it can be formed by asputtering method using an ITO containing silicon as a target. At thetime, siloxane may be employed for the interlayer insulating film 121.Further, an insulating film containing nitrogen 126, e.g. siliconnitride or silicon oxynitride may be formed on the interlayer insulatingfilm of siloxane. When a light-emitting element having such a structureis formed, light-emitting intensity and an endurance time can beimproved. When acryl or polyimide is used for the interlayer insulatingfilm 121, the insulating film containing nitrogen 126 can be eliminated.In such a structure, a liquid element may be formed.

When the pixel electrode is formed by an ink-jetting method, as a resultof the liquid-repellent treatment and the selective lyophilic treatment,the pixel electrode formed by an ink-jetting method can be miniaturized.After that, a heat treatment for baking or drying is conducted when thesolvent of the dot is required to remove.

In this way, when the pixel electrode is formed by an ink-jettingmethod, a liquid-repellent treatment and a selective lyophilic-treatmentare preferably performed on a surface for forming the pixel electrode.

As described above, by the liquid-repellent treatment and the selectivelyophilic treatment before an ink-jetting step, a thin film transistorhaving a miniaturized pixel electrode can be obtained.

A TFT substrate in which up to a pixel electrode has been formed isreferred to as a module TFT substrate.

Embodiment Mode 12

A display device including a liquid crystal module having a thin filmtransistor (a liquid crystal display device) shown in the embodimentmodes described above is described in Embodiment Mode 12.

FIG. 8 is a cross-sectional view of a liquid crystal display devicehaving a thin film transistor 120 and a pixel electrode 125 formed overa TFT substrate as described in the embodiment modes. When alight-transmitting conductive film (such as ITO or ITSO) is used for thepixel electrode 125, a transmissive liquid crystal display device can beobtained. On the contrary, when a non light-transmitting film, that is,a high-reflective film (e.g., aluminum) is used, a reflective liquidcrystal display device can be obtained. A module TFT substrate used fora liquid crystal display device like this embodiment mode is referred toas a liquid crystal module TFT substrate.

An orientation film 131 is formed to cover the thin film transistor 120,a protective film 113, and the pixel electrode 125.

A color filter 134, an opposite electrode 133, and the orientation film131 are formed sequentially over an opposite substrate 135. The colorfilter, the opposite electrode or the orientation film can be formed byan ink-jetting method. Although not shown, a black matrix may be alsoformed by an ink-jetting method.

After that, the substrate 100 is attached to the opposite substrate 135by a sealing material and a liquid crystal is injected thereinto to forma liquid crystal layer 136, thereby obtaining a liquid crystal module.When the liquid crystal is injected, a treatment chamber that is to bein a vacuum state is required.

Note that a liquid crystal may be dropped and an ink-jetting method maybe employed for the dropping method of a liquid crystal. In particular,in the case of a large-size substrate, a liquid crystal is preferablydropped. This is because a larger treatment chamber is required, asubstrate weighs more and a treatment is more difficult as a substratebecomes larger, in the case of a liquid crystal injection method.

When a liquid crystal is dropped, a sealing material is formed in theperiphery of one substrate. The reason why one substrate is described isthat the sealing material may be formed in either the substrate 100 orthe opposite substrate 135. At the time, the sealing material is formedin the closed area where the end point is accorded with the initialpoint of the sealing material. After that, one drop or more drops ofliquid crystals is/are dropped. In the case of a large-size substrate,plural drops of liquid crystals are dropped in plural portions. Then,the substrate is attached to the other substrate in vacuum. This isbecause it is possible to remove unnecessary air and to prevent asealing material from being broken and expanded due to air, by makingthe vacuum state.

Then, two or more points in the region where the sealing material isformed are solidified and bonded for temporary attachment. Two or morepoints in the region where the sealing material is formed may beirradiated with ultraviolet rays, when ultraviolet curable resin is usedfor the sealing material. After that, the substrate is taken out of thetreatment chamber, and the whole sealing material is solidified andbonded so as to completely be attached. At the time, a light-shieldingmaterial is preferably arranged so that a thin film transistor or aliquid crystal may not be irradiated with ultraviolet rays.

A pillar like or spherical spacer may be used as well as the sealingmaterial so as to keep the gap between the substrates.

In this manner, a liquid crystal module is completed.

After that, an external terminal may be connected to a signal linedriver circuit or a scanning line driver circuit by bonding an FPC(Flexible Printed Circuit) using anisotropic conductive film. Further,the signal line driver circuit or the scanning line driver circuit maybe formed as an external circuit.

In this manner, a liquid crystal display device in which a thin filmtransistor having a miniaturized wiring is provided and to which anexternal terminal is connected, can be formed.

In this embodiment mode, a very thin liquid crystal display device canbe formed, since the thin film transistor does not include an interlayerinsulating film.

An interlayer insulating film may be formed to increase planarity, asshown in the above embodiment modes, in this embodiment mode. When theplanarity is increased, an orientation film can be formed uniformly andvoltage can be applied to a liquid crystal layer uniformly, which ispreferable.

As the interlayer insulating film, an inorganic material (such assilicon oxide, silicon nitride, silicon oxynitride), a photosensitive ornon-photosensitive organic material (such as polyimide, acryl,polyamide, polyimidamide, benzocyclobutene or resist), siloxane,polysilazane and a laminated structure thereof can be used. As theorganic material, positive type photosensitive organic resin or negativephotosensitive organic resin can be used.

Embodiment Mode 13

A display device (a light emitting device) having a light emittingmodule including a thin film transistor shown in the above describedembodiment modes is described in Embodiment Mode 13.

FIG. 10 is a cross-sectional view of a light emitting device having athin film transistor 120 and a pixel electrode 125 formed in the TFTsubstrate shown in the foregoing embodiment modes.

The thin film transistor 120 having the pixel electrode 125 is formed asshown in the above embodiment modes. The pixel electrode 125 functionsas a first electrode of a light-emitting element.

After that, an insulating film 143 functioning as a bank or a barrier isformed over the first electrode. As the insulating film, an inorganicmaterial (such as silicon oxide, silicon nitride, silicon oxynitride), aphotosensitive or non-photosensitive organic material (such aspolyimide, acryl, polyamide, polyimidamide, benzocyclobutene or resist),siloxane, polysilazane and a laminated structure thereof can be used. Asthe organic material, positive photosensitive organic resin or negativephotosensitive organic resin can be used. For example, in the case ofusing positive photosensitive acrylic as the organic material, thephotosensitive organic resin is etched by light-exposure to form anopening portion with a curvature in the upper edge portion. This canprevent an electroluminescent layer to be formed later or the like frombeing disconnected. The TFT substrate in this state is referred to as alight emitting module TFT substrate.

An electroluminescent layer 141 is formed in the opening portion of theinsulating film 143 formed over the first electrode. A liquid-repellenttreatment may be performed by a plasma treatment before forming theelectroluminescent layer. Further, a lyophilic region may be formedselectively by laser irradiation in the opening portion of theinsulating film in the liquid-repellent region. In this embodiment mode,a plasma treatment is performed on the opening portion of the insulatingfilm 143 and the electroluminescent layer having a high molecular weight(polymeric) material is formed by an ink-jetting method.

Thereafter, a second electrode 142 of the light-emitting element isformed to cover the electroluminescent layer 141 and the insulating film143.

A singlet excited state and a triplet excited state are possible as akind of the molecular exciton formed by an electroluminescent layer. Aground state is generally a singlet excited state, and light emissionfrom a singlet excited state is referred to as fluorescence. Lightemission from a triplet excited state is referred to as phosphorescence.Light-emission from an electroluminescent layer includes light emissionby the both excited states. Further, fluorescence and phosphorescencemay be combined, and either of them can be selected depending onluminescence property (such as light-emitting intensity or a ifetime) ofrespective RGB.

The electroluminescent layer 141 is formed by laminating in order HIL(hole injecting layer), HTL (hole transporting layer), EML (lightemitting layer), ETL (electron transporting layer), EIL (electroninjecting layer) sequentially from the first electrode sidecorresponding to the pixel electrode 125. Note that theelectroluminescent layer can employ a single layer structure or acombined structure other than a laminated structure.

Materials for light emission of red (R) green (G) and blue (B) are eachselectively formed by a vapor deposition method using a vapor-depositionmask, or the like for the electroluminescent layer 141. The materialsfor light emission of red (R) green (G) and blue (B) can be formed alsoby an ink-jetting method, and this case is preferable since it ispossible to individually apply each RGB without using a mask.

Specifically, CuPc or PEDOT for HIL α-NPD for HTL, BCP or Alq₃ for ETLand BCP: Li or CaF₂ for EIL are used respectively. Alq₃ doped with adopant corresponding to each light emission of RGB (DCM or the like forR, DMQD or the like for (G) may be used for EML, for example.

Note that the electroluminescent layer is not limited to the abovematerial. For example, a hole injection property can be enhanced byco-evaporating oxide such as molybdenum oxide (MoOx: x=2 to 3) and α-NPDor rubrene instead of using CuPc or PEDOT. An organic material(including a low molecular weight material or a high molecular weightmaterial) or a composite material of an organic material and aninorganic material can be used as the material of the electroluminescentlayer.

In the case of forming the electroluminescent layer of each RGB,high-definition display can be performed by using a color filter. Thisis because broad peak can be corrected to be sharp in light emittingspectrum of each RGB by the color filter.

The case of forming materials for light emission of each RGB isdescribed above, but a material for monochrome light emission is formedand a color filter or a color conversion layer is combined to displaywith full color. For example, when an electroluminescent layer for lightemission of white or orange is formed, a color filter, or a color filtercombined with a color conversion layer is provided separately to obtaina full color display. A color filter or a color conversion layer may beformed on a second substrate (sealing substrate), for example, andattached to a substrate. A material for monochrome light emission, acolor filter, and a color conversion layer can be each formed by anink-jetting method.

A display of monochrome light emission may be performed. For example, anarea color type display device may be formed by using monochrome lightemission. A passive matrix display portion is suitable for the areacolor type, which can mainly display characters and symbols.

In addition, it is necessary to select materials of the first electrode125 and the second electrode 142 in consideration of the work function.However, the first electrode and the second electrode can be an anode ora cathode depending on a pixel structure. It is preferable that thefirst electrode is a cathode and the second electrode is an anode inthis embodiment mode, since the polarity of a driving TFT is an Nchannel type. On the contrary, it is preferable that the first electrodeis an anode and the second electrode is a cathode when the polarity ofthe driving TFT is a P channel type.

Hereinafter, electrode materials used for the anode and the cathode aredescribed.

It is preferable to use a metal, an alloy, a conductive compound, amixture thereof, or the like having a high work function (work function:4.0 eV or more) as an electrode material used for the anode. ITO (indiumtin oxide), IZO (indium zinc oxide) in which zinc oxide (ZnO) of from 2%to 20% is mixed into indium oxide, ITSO in which silicon oxide (SiO₂) offrom 2% to 20% is mixed into indium oxide, gold, platinum, nickel,tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, anitride of a metal material (such as titanium nitride) and the like canbe cited as a specific material.

On the other hand, it is preferable to use a metal, an alloy, aconductive compound, a mixture thereof, or the like having a low workfunction (work function: 3.8 eV or less) as an electrode material usedfor the cathode. An element belonging to Group 1 or 2 in the periodictable, that is, an alkaline metal such as lithium or cesium, an alkalineearth metal such as magnesium, calcium, or strontium, an alloy (Mg:Ag orAl:Li) or a compound (LiF, CsF, or CaF₂) including them, or a transitionmetal including a rare-earth metal can be cited as a specific material.

The second electrode can be formed by extremely thinly forming such ametal or an alloy including such a metal and by laminating ITO, IZO,ITSO, or another metal (including an alloy) thereover, when the secondelectrode is required to be light transmitting in this embodiment mode.

The first electrode and the second electrode can be formed by a vapordeposition method, a sputtering method, an ink-jet method, or the like.

In the case of forming a conductive film, ITO or ITSO, or a laminatedbody thereof as the second electrode by a sputtering method, theelectroluminescent layer may be damaged from the sputtering. In order toreduce damages from the sputtering method, an oxide such as molybdenumoxide (MoOx: x=2 to 3) is preferably formed on a top surface of theelectroluminescent layer. Therefore, oxide such as molybdenum oxide(MoOx: x=2 to 3) which functions as HIL or the like is formed on a topface of the electroluminescent layer. An EIL (electron injecting layer),an ETL (electron transporting layer), an EML (light emitting layer), anHTL (hole transporting layer), an HIL (hole injecting layer), and thesecond electrode may be laminated in this order from a side of the firstelectrode. At this time, the first electrode functions as a cathode andthe second electrode functions as an anode.

Since the polarity of the driving TFT is an N channel type in thisembodiment mode, it is preferable to employ a structure of the firstelectrode that is a cathode, EIL (electron injecting layer), ETL(electron transporting layer), EML (light emitting layer), HTL (holetransporting layer), HIL (hole injecting layer), and the secondelectrode that is an anode in consideration of a moving direction of anelectron.

Thereafter, a passivation film containing nitrogen, a DLC (Diamond likecarbon), or the like may be formed by a sputtering method or a CVDmethod. Accordingly, penetration of moisture and oxygen can beprevented. In addition, penetration of oxygen or moisture can beprevented by covering a side face of a display device with the firstelectrode, the second electrode, or another electrode. Subsequently, asealing substrate is attached. A space formed by the sealing substratemay be encapsulated with nitrogen or may be provided with a desiccantagent. In addition, light transmitting and highly water-absorbing resinmay be filled therein. The sealing structure is described in detail inan embodiment mode hereafter.

A light emitting module is completed in this manner.

In the light emitting module, when the first electrode and the secondelectrode are formed to be light-transmitting, light is emitted from theelectroluminescent layer in the directions shown by both arrows 145 and146, with a brightness corresponding to a video signal inputted from asingle line. When the first electrode is light-transmitting and thesecond electrode is not light-transmitting, light is emitted only in thedirection of the arrow 146. When the first electrode is notlight-transmitting and the second electrode is light-transmitting, lightis emitted only in the direction of the arrow 145. At the time, lightcan be efficiently utilized by using a highly reflective conductive filmas the non-light-transmitting electrode provided on a side which is nota light emitting direction.

In this embodiment mode, a non-light-transmitting conductive film may beformed to be thin enough to transmit light and a light-transmittingconductive film may be laminated thereover, so as to obtain a conductivefilm having a light-transmitting property.

After that, an external terminal may be connected to a signal linedriver circuit or a scanning line driver circuit by bonding an FPC(flexible printed circuit) using anisotropic conductive film. Further,the signal line driver circuit or the scanning line driver circuit maybe formed as an external circuit.

Like this, a light-emitting display device in which a thin filmtransistor having a miniaturized wiring is provided and to which anexternal terminal is connected, can be formed.

In this embodiment mode, a very thin light-emitting display device canbe formed, since the thin film transistor does not include an interlayerinsulating film.

An interlayer insulating film may be formed to increase planarity, asshown in the above embodiment modes, in this embodiment mode. It ispreferable that the planarity is increased and thus, voltage can beapplied to the electroluminescent layer uniformly.

As the interlayer insulating film, an inorganic material (such assilicon oxide, silicon nitride, silicon oxynitride), a photosensitive ornon-photosensitive organic material (such as polyimide, acryl,polyamide, polyimidamide, benzocyclobutene or resist), siloxane,polysilazane and a laminated structure thereof can be used. As theorganic material, positive type photosensitive organic resin or negativephotosensitive organic resin can be used.

FIG. 9A illustrates an equivalent circuit diagram of a pixel portion ofa light emitting device. One pixel includes a TFT for switching(switching TFT) 800, a TFT for driving (driving TFT) 801, and a TFT forcontrolling current (current controlling TFT) 802. Theses TFTs are Nchannel types. One electrode and a gate electrode of the switching TFT800 are connected to a signal line 803 and a scanning line 805,respectively. One electrode of the current controlling TFT 802 isconnected to a first power supply line 804, and a gate electrode thereofis connected to the other electrode of the switching TFT.

A capacitor element 808 may be provided to hold gate-source voltage ofthe current controlling TFT. In this embodiment mode, when electricpotential of the first power supply line is low and that of a lightemitting element is high, the current controlling TFT is an N channeltype. Therefore, the source electrode and the first power supply lineare connected. Therefore, the capacitor element can be provided betweenthe gate electrode and a source electrode of the current controllingTFT, that is, the first power supply line. When the switching TFT, thedriving TFT, or the current controlling TFT has a high gate capacitanceand leak current from each TFT is permissible, the capacitor element 808is not necessarily provided.

One electrode of the driving TFT 801 is connected to the other electrodeof the current controlling TFT, and the gate electrode thereof isconnected to a second power supply line 806. The second power supplyline 806 has a fixed electric potential. Therefore, a gate electricpotential of the driving TFT can be fixed, and the driving TFT can beoperated, so that gate-source voltage Vgs is not changed by parasiticcapacitance or wiring capacitance.

Then, a light emitting element 807 is connected to the other electrodeof the driving TFT. In this embodiment mode, when an electric potentialof the first power supply line is low and that of the light emittingelement is high, a cathode of the light emitting element is connected toa drain electrode of the driving TFT. Therefore, it is preferable tosequentially laminate a cathode, an electroluminescent layer and ananode. At this time, in order to reduce damages from sputtering informing the second electrode, an oxide such as a molybdenum oxide (MoOx:x=2 to 3) is preferably formed on a top surface of theelectroluminescent layer. Therefore, it is more preferable to form oxidesuch as molybdenum oxide (MoOx: x=2 to 3) which functions as an HIL orthe like on a top surface of the electroluminescent layer. In this way,in the case of a TFT having an amorphous semiconductor film and an Nchannel type, it is preferable to connect the drain electrode of the TFTand the cathode and to laminate an EIL, an ETL, an EML an HTL an HIL,and anode in this order.

Hereinafter, operation of such a pixel circuit is described.

When the scanning line 805 is selected and the switching TFT is turnedON, charges begin to be stored in the capacitor element 808. The chargesare stored in the capacitor element 808 until they become equal togate-source voltage of the current controlling TFT. When they are equal,the current controlling TFT is turned ON, and then, the driving TFT thatis serially connected thereto is turned ON. At this time, the gatepotential of the driving TFT is fixed. Therefore, constant gate-sourcevoltage Vgs which does not depend on the parasitic capacitance or thewiring capacitance can be applied to the light emitting element. Inother words, current by the constant gate-source voltage Vgs can besupplied.

Since the light emitting element is a current driving type element, itis preferable to employ analog driving when characteristic variation ofthe TFT in the pixel, specifically, Vth variation is small. As in thisembodiment mode, a TFT having an amorphous semiconductor film has smallcharacteristics variation; therefore, analog driving can be employed. Onthe other hand, current at a constant value can be supplied to the lightemitting element, also in the case of digital driving, by operating thedriving TFT in a saturation region (a region satisfying|Vgs-Vth⊕<|Vds|).

FIG. 9B shows an example of a top view of a pixel portion having theabove equivalent circuit.

A gate electrode, a scanning line, and a second power supply line ofeach TFT are formed from the same conductive film over a base film by anink-jetting method or a sputtering method. When the gate electrode orthe like is formed by an ink-jetting method, a plasma treatment may beperformed on the base film that is a surface for forming the gateelectrode or the like to form a liquid-repellent region. Further, alyophilic region may be formed selectively in the liquid-repellentregion to form a gate electrode, a scanning line and a second powersupply line therein. Consequently, the gate electrode, the scanning lineand the second power supply line that are formed by an ink-jettingmethod can be miniaturized.

Although not shown, a gate insulating film is formed after that.

A first electrode 810 of the light emitting element 807 is formed on thegate insulating film. The first electrode 810 can be formed by anink-jetting method, a sputtering method or the like. When the firstelectrode is formed by an ink-jetting method, a plasma treatment isconducted on the gate insulating film that is a surface for forming thefirst electrode to form a liquid-repellent region. Further, a lyophilicregion may be formed selectively in the liquid-repellent region to formthe first electrode therein. Consequently, the first electrode formed byan ink-jetting method can be miniaturized.

Then, a semiconductor film is formed. The semiconductor film is formedover the entire surface by plasma CVD and pattered into a desired shapeusing a mask in this embodiment mode. A semiconductor film having N typeconductivity may be formed on the semiconductor film, namely thesemiconductor film and the semiconductor film having N type conductivitycan be continuously formed.

After that, the conductive film formed by sputtering or CVD is patternedto form a source wiring, a drain wiring, a signal line and a first powersupply line. A mask used in patterning can be formed by an ink-jettingmethod or a photolithography method.

The source wiring, the drain wiring, the signal line and the first powersupply line can be formed by an ink-jetting method. When the sourcewiring, the drain wiring, the signal line and the first power supplyline are formed by an ink-jetting method, a plasma treatment isconducted on a surface for forming each the source wiring, the drainwiring, the signal line and the first power supply line to form aliquid-repellent region. Further, a lyophilic region may be formedselectively in the liquid-repellent region to form the source wiring,the drain wiring, the signal line and the first power supply linetherein. Consequently, the source wiring, the drain wiring, the signalline and the first power supply line formed by an ink-jetting method canbe miniaturized.

In this embodiment mode, the capacitor element 808 is formed from thegate wiring and the source and drain wiring which are formed with thegate insulating film therebetween.

In this embodiment mode, a channel width (W) of the driving TFT may bedesigned to be large, since the driving TFT includes an amorphoussemiconductor film.

In this way, a pixel portion of the light-emitting device can be formed.

A cross-sectional view of C-C′ of FIG. 9B is shown in FIG. 10.

The active matrix light-emitting device like this is effective since aTFT is provided for every pixel and thus it can be driven with lowvoltage, when a pixel density is increased.

Although this embodiment mode shows an active matrix light-emittingdevice in which each TFT is formed in one pixel, a passive matrix lightemitting device in which a TFT is formed in every column can be alsoformed. In the passive matrix light emitting device, a high apertureratio can be obtained since a TFT is not provided for every pixel. In alight emitting device in which light is emitted toward opposite sides ofan electroluminescent layer, light transmittance can be increased byemploying a passive matrix light emitting device.

Embodiment Mode 14

A mode of a display device such as a light emitting device or a liquidcrystal display device connected with an external terminal is describedin Embodiment Mode 14.

FIG. 11 shows an appearance of a display device on which a controlcircuit 601 a and a power supply circuit 602 are mounted. A pixelportion 603 in which a light emitting element or a liquid crystalelement is provided for every pixel is formed on a substrate 600. A thinfilm transistor in the pixel portion 603 can be formed to have a wiringor the like that is miniaturized as in the foregoing embodiment modes. Ascanning line driver circuit 604 a for selecting a pixel of the pixelportion 603 and a signal line driver circuit 605 a for supplying a videosignal to the selected pixel are mounted by an IC chip. Widths of longand short sides of an IC to be mounted or the number thereof is notlimited to those described in this embodiment mode. The scanning linedriver circuit or the signal line driver circuit may be integrallyformed with the pixel portion.

The control circuit 601 a, the power supply circuit 602, an image signalprocessing circuit 609 a, a video RAM 610 a, and an audio circuit 611 aare provided for a printed wiring board 607. A power supply voltageoutputted from the power supply circuit 602, or various signals from thecontrol circuit 601 a, the image signal processing circuit 609 a, thevideo RAM 610 a, and the audio circuit 611 a are supplied into thescanning line driver circuit 604 a and the signal line driver circuit605 a through an FPC 606, and further are supplied to the pixel portion603.

The power supply voltage of the printed wiring board 607 and varioussignals are supplied through an interface (I/F) portion 608 in whichplural input terminals are arranged. A signal is inputted into the imagesignal processing circuit 609 a from the interface (I/F) portion 608. Asignal is sent and received between the image signal processing circuit609 a and the video RAM 610 a.

Note that the printed wiring board 607 is mounted by using the FPC 606in this embodiment mode; however, the present invention is notnecessarily limited to this structure. The control circuit 601 a and thepower supply circuit 602 may be mounted directly on the substrate by aCOG (Chip On Glass) method. In addition, a mounting method of an IC chipsuch as the signal line driver circuit and the scanning line drivercircuit is not limited to this embodiment mode, and an IC chip formed onthe substrate may be connected to a wiring in the pixel portion by awire bonding method.

Further, in the printed wiring board 607, noise may be caused in thepower supply voltage or signals, or the rise of the signal may becomeslow due to capacitance formed between leading wirings, resistance ofthe wiring itself, and the like. Thus, various kinds of elements such asa capacitor and a buffer may be provided on the printed wiring board607, thereby preventing noise from being caused in the power supplyvoltage or signals, or preventing the rise of the signal from beingslow.

As described above, a display device provided with a thin filmtransistor having a miniaturized wiring or the like can be manufactured.

A mode of a display device different from that in FIG. 11 is shown inFIGS. 19A and 19B. In FIGS. 19A and 19B, a module is formed from a thinfilm transistor having a crystalline semiconductor film as shown inEmbodiment Mode 5. Thus, an element formed in a driver circuit portionor a peripheral circuitry portion can be integrally formed on asubstrate.

As shown in FIG. 19A, a pixel portion 603, a scanning line drivercircuit 604 b, a signal line driver circuit 605 b, a control circuit 601b, an audio circuit 611 b, an image signal processing circuit 609 b, anda video RAM 610 b are provided on a substrate 600. Accordingly, thenumber of elements formed on a printed wiring board can be reduced.

A block diagram of each circuit formed on the substrate 600 is shown inFIG. 19B. A circuit in which a liquid crystal element is formed in thepixel portion 603 is described. The pixel portion 603 is provided on apanel and a gray-scale power supply 617 for displaying with gray-scaleis also formed on the panel. In the periphery of the pixel portion 603,a scanning line driver circuit 604 a and a signal line driver circuit605 a are provided.

The control circuit 601 b includes a CPU 616, a CPU interface (I/F) 623,a WRAM 624 serving as a stack/variable SRAM used by the CPU, a PROM 615serving as a mask ROM storing a program and image data, and a memorycontroller 625. The memory controller 625 has a function for making asignal for controlling the audio circuit by decoding an interface ofaddress/data pass of PROM and WRAM, and a part of an address signal forWRAM.

The audio circuit 611 b includes an audio ROM 619 functioning as a maskROM in which audio data is stored, an audio controller 621 having afunction of forming a clock signal for the audio circuit or forming anaddress for the audio ROM using a counter, and an amplifier 618 having afunction of forming analog waveform from digital audio data oramplifying the analog waveform.

The image signal processing circuit 609 b includes a CRAM 622 serving asa SRAM storing color information of image data.

An SRAM 626 storing coordinate information of an image or imageinformation for an image of one line is also provided.

Power from the power supply circuit 602 formed on the printed wiringboard 607 is supplied to the respective circuits having these functionsthrough the FPC 606.

When a thin film transistor is manufactured by using a crystallinesemiconductor film like this, it can be integrally formed on a glasssubstrate, and thus, downsizing and reducing in weight of a displaydevice can be achieved. Productivity of a display device can beincreased, since the number of connecting points with FPC can bereduced.

As described above, a display device provided with a thin filmtransistor having a miniaturized wiring or the like can be manufactured.

Embodiment Mode 15

A mode of sealing a light emitting device shown in the foregoingembodiment modes is shown in Embodiment Mode 15.

FIG. 12A is a cross-sectional view of a sealed light-emitting device,and a cross-sectional view taken along D-D′ of FIG. 11. In a pixelportion 903, a driving TFT 914 having an N-channel is provided over asubstrate 911 (referred to as a first substrate for convenience) with abase film 912 therebetween. The driving TFT can be formed to have awiring or the like miniaturized in the foregoing embodiment modes. Ananode 915 is connected to a wiring to serve as a source electrode or adrain electrode of the driving TFT. An electroluminescent layer 916 anda cathode 917 are formed in order over the anode.

A protective film 918 is further provided to cover the cathode. Theprotective film is formed to have an insulating film that mainlycontains silicon nitride or silicon oxynitride and that is obtained by asputtering method (DC method or RF method), a DLC film containinghydrogen, or a carbon nitride film. The protective film can have asingle layer structure or a laminated structure of the above films. Forexample, when a film having high hardness is used to prevent entrance ofwater or oxygen as the protective film, it is possible that a film forrelaxing stress, e.g., a carbon nitride film is formed and then, a filmhaving high hardness is formed thereover. Deterioration (degradation) ofan electroluminescent layer by water, oxygen or the like can beprevented by the protective film.

The cathode and the protective film are provided to exist also in thefirst connection region 920. In the connection region 920, the cathodeis connected to a connection wiring 919.

In a sealing region 923, the first substrate 911 is attached to anopposite substrate 922 (referred to as a second substrate forconvenience) by a sealing material 921. The opposite substrate may beprovided with a desiccant agent 925. By the desiccant agent, entrance ofwater or oxygen can be prevented. A color filter may be provided for theopposite substrate. A broad peak can be corrected to be sharp in lightemitting spectrum of each RGB by the color filter. The sealing materialis made of thermosetting resin or ultraviolet curable resin. The firstsubstrate and the second substrate are adhered and fixed by heating thesealing material while pressuring or by ultraviolet irradiation. Forexample, epoxy based resin can be employed as the sealing material. Thesealing material is mixed with a spacer. The space (that is, a gap)between the first substrate and the second substrate is maintained bythe spacer of the sealing material. The spacer may be spherical orcolumn-like, and a cylindrical spacer is used in this embodiment mode,and thus, the gap is equivalent to a diameter of the circle.

In a second connection region 926, a connection wiring 919 is connectedto a signal line driver circuit formed from an IC chip 927 by ananisotropic conductive film 924. The IC chip is provided on the FPC 906.When the anisotropic conductive film is adhered by heating orpressuring, it is conducted carefully so that a crack is not generateddue to a flexibility of a film substrate or softening by heating. Forexample, a substrate having high hardness may be arranged as anauxiliary in the adhering region. A clock signal, or a video signal isreceived from the thusly connected IC chip.

When the light emitting device is sealed with the second substrate 922,a space is formed between the second substrate 922 and the protectivefilm 918. It is possible to further prevent entrance of water or oxygenby filling an inert gas, e.g. a nitrogen gas or forming a highlywater-absorbing material in the space. Light-transmitting and highlywater-absorbing resin may be formed. The light emitting device can beformed by using light-transmitting resin without reducinglight-transmittance, even when light from a light emitting element isemitted toward the second substrate side.

FIG. 12B shows a mode of sealing without using a second substrate, whichis different from that of FIG. 12A. Other structures are similar, andthus description thereof is omitted.

In FIG. 12B, a second protective film 930 is provided to cover aprotective film 918. An organic material such as epoxy resin, urethaneresin or silicone resin can be used as the second protective film. Thesecond protective film may be formed by dropping a polymeric(high-molecular-weight) material by an ink-jetting method. Epoxy resinis discharged by a dispenser and dried in this embodiment mode.

When deterioration of an electroluminescent layer due to water, oxygenor the like does not matter, the protective film 918 may not benecessarily provided. A second substrate may be provided over the secondprotective film for sealing.

When the light emitting device is sealed without using the secondsubstrate, it is possible to reduce more in weight, size and thicknessof a display device.

A polarizing plate or a circular polarizing plate may be provided toincrease contrast in this embodiment mode. For example, a polarizingplate or a circular polarizing plate can be provided for one surface orboth surfaces of a display screen.

Embodiment Mode 16

Examples of electronic devices using a display device described in theabove embodiment modes can be given as follows: a video camera; adigital camera; a goggle type display (head mounted display); anavigation system; an audio reproducing device (such as a car audio oran audio component); a laptop personal computer; a game machine; apersonal digital assistance (such as a mobile computer, a cellularphone, a portable game machine or an electronic book); an imagereproducing device including a recording medium (specifically, a devicecapable of reproducing a recording medium such as a Digital VersatileDisc (DVD) and having a display that can display the image); and thelike. Specifically, an ink-jetting method described in the aboveembodiment modes is preferably applied to a large-size television havinga large screen, and the like. Practical examples of these electronicdevices are shown in FIGS. 13A to 13C.

FIG. 13A shows a large-size display device, which includes a chassis2001, a supporting section 2002, a display portion 2003, a speakerportion 2004, a video input terminal 2005, and the like. The displayportion 2003 is provided with a module including a pixel portion and adriver circuit portion. The pixel portion has a light emitting elementor a liquid crystal element and a TFT formed by an ink-jetting methoddescribed in the above embodiment modes. Note that the display deviceincludes all display devices for displaying information such as adisplay device for a personal computer, a display device for TVbroadcasting reception, and a display device for advertisement.

FIG. 13B shows a cellular phone that is one of mobile terminals, whichincludes a main body 2101, a chassis 2102, a display portion 2103, anaudio input portion 2104, an audio output portion 2105, operation keys2106, antenna 2107, and the like. The display portion 2103 is providedwith a module including a pixel portion and a driver circuit portion.The pixel portion has a light emitting element or a liquid crystalelement and a TFT formed by an ink-jetting method described in the aboveembodiment modes. In addition, costs of the cellular phone can bereduced by forming the display portion 2103 by a method of formingplural panels from one substrate (gang printing).

FIG. 13C shows a sheet-like cellular phone, which includes a main body2301, a display portion 2303, an audio input portion 2304, an audiooutput portion 2305, a switch 2306, an external connection port 2307,and the like. A separately prepared earphone 2308 can be connected tothe cellular phone through the external connection port 2307. A touchpanel display screen with a sensor is used for the display portion 2303.A series of operation can be performed by touching the touch paneloperation key 2309 displayed on the display portion 2303. The displayportion 2303 is provided with a module having a pixel portion and adriver circuit portion. The pixel portion has a light emitting elementor a liquid crystal element and a TFT formed by an ink-jetting methoddescribed in the above embodiment modes. In addition, costs of thesheet-like cellular phone can be reduced by forming the display portion2303 by a method of forming plural panels from one substrate (gangprinting).

As described above, an applicable range of the present invention is sowide that it can be applied to electronic devices of various fields. Inaddition, the electronic devices of this embodiment mode can employ anystructure described in the above embodiment modes.

Embodiment Mode 17

An inert gas can be employed as a treatment gas of a plasma treatment inthe present invention. A rare gas such as helium (He), neon (Ne), argon(Ar), krypton (Kr), xenon (Xe) can be used as the inert gas. Otherconditions such as pressure are similar to those described in theforegoing embodiment modes.

1. A method for forming a wiring comprising the steps of: performing aliquid-repellent treatment on a surface; performing selectively alyophilic treatment on a region of the surface; and forming a wiring onthe lyophilic region by dropping a composition including a conductivematerial.
 2. A method for forming a wiring comprising the steps of:forming a liquid-repellent region on a surface; forming selectively alyophilic region in the liquid-repellent region; and forming the wiringon the lyophilic region by dropping a composition including a conductivematerial.
 3. A method for forming a wiring comprising the steps of:forming a liquid-repellent region on a surface by a plasma treatment;forming selectively a lyophilic region in the liquid-repellent region;and forming the wiring on the lyophilic region by dropping a compositionincluding a conductive material.
 4. The method for forming a wiringaccording to claim 3, wherein the plasma treatment is performed at apressure of 100 Torr to 1000 Torr.
 5. The method for forming a wiringaccording to claim 4, wherein the plasma treatment is performed under anatmospheric pressure or a pressure in a neighborhood of an atmosphericpressure by using air, oxygen or nitrogen as a treatment gas.
 6. Themethod for forming a wiring according to claims 2 or 3, wherein thelyophilic region is selectively formed by irradiating theliquid-repellent region with laser light.
 7. The method for forming awiring according to claims 2 or 3, wherein a region that is lessliquid-repellent than the liquid-repellent region is formed as thelyophilic region.
 8. The method for forming a wiring according to anyone of claims 1 to 3, wherein the composition is dropped by anink-jetting method.
 9. A method for forming a wiring comprising thesteps of: forming a liquid-repellent region by forming a film containingfluorine on a surface; forming selectively a lyophilic region in theliquid-repellent region; and forming the wiring on the lyophilic regionby dropping a composition including a conductive material.
 10. Themethod for forming a wiring according to claim 9, wherein a Teflon filmor a silane coupling agent is formed to form the liquid-repellentregion.
 11. The method for forming a wiring according to claims 9 or 10,wherein the lyophilic region is selectively formed by irradiating theliquid-repellent region with laser light.
 12. The method for forming awiring according to claims 9 or 10, wherein a region that is lessliquid-repellent than the liquid-repellent region is formed as thelyophilic region.
 13. The method for forming a wiring according toclaims 9 or 10, wherein the composition is dropped by an ink-jettingmethod.
 14. A method for manufacturing a thin film transistor comprisingthe steps of: performing a liquid-repellent treatment on a surface;performing selectively a lyophilic treatment on a region of the surface;and forming a conductive film on the lyophilic treatment by dropping acomposition including a conductive material.
 15. A method formanufacturing a thin film transistor comprising the steps of: forming aliquid-repellent region on a surface; forming selectively a lyophilicregion in the liquid-repellent region, and forming the conductive filmon the lyophilic region by dropping a composition including a conductivematerial.
 16. A method for manufacturing a thin film transistorcomprising the steps of: forming a first liquid-repellent region byperforming a plasma treatment on a surface for forming a gate electrode;forming selectively a first lyophilic region in the firstliquid-repellent region; forming the gate electrode in the firstlyophilic region by dropping a composition including a conductivematerial; forming a second liquid-repellent region by a plasma treatmenton a surface for forming a source electrode and a drain electrode;forming selectively a second lyophilic region in the secondliquid-repellent region; and forming the source electrode and the drainelectrode in the second lyophilic region by dropping a compositionincluding a conductive material.
 17. A method for manufacturing a thinfilm transistor comprising the steps of: forming a firstliquid-repellent region by performing a plasma treatment on a substrate;forming selectively a first lyophilic region in the firstliquid-repellent region; forming a gate electrode in the first lyophilicregion of the substrate by dropping a composition including a conductivematerial; forming a gate insulating film to cover the gate electrode;forming a semiconductor film over the gate electrode; forming asemiconductor film having one conductivity over the semiconductor film;forming a second liquid-repellent region by a plasma treatment on thesemiconductor film having one conductivity and the gate insulating film;forming selectively a second lyophilic region in the secondliquid-repellent region; and forming a source electrode and a drainelectrode in the second lyophilic region of the semiconductor filmhaving one conductivity and the gate insulating film by dropping acomposition including a conductive material.
 18. A method formanufacturing a thin film transistor, comprising the steps of: forming asource electrode and a drain electrode; forming a semiconductor filmover the source electrode and the drain electrode; forming aliquid-repellent region by performing a plasma treatment on a surfacefor forming a gate electrode in an upper portion of the semiconductorfilm; forming selectively a lyophilic region in the liquid-repellentregion; and forming the gate electrode in the lyophilic region of thesurface of the gate electrode by dropping a composition including aconductive material.
 19. A method for manufacturing a thin filmtransistor, comprising the steps of: forming a source electrode and adrain electrode over a base film; forming a semiconductor film over thesource electrode and the drain electrode; forming a firstliquid-repellent region by performing a plasma treatment on thesemiconductor film; forming selectively a first lyophilic region in thefirst liquid-repellent region; forming a mask in the lyophilic region ofthe semiconductor film by dropping a composition including a material ofthe mask; patterning the semiconductor film by using the mask; forming agate insulating film to cover the semiconductor film; forming a secondliquid-repellent region by performing a plasma treatment on the gateinsulating film; forming selectively a second lyophilic region in thesecond liquid-repellent region; and forming a gate electrode in thesecond lyophilic region of the gate insulating film by dropping acomposition including a conductive material.
 20. A method formanufacturing a thin film transistor comprising the steps of: forming afirst liquid-repellent region by performing a plasma treatment on a basefilm; forming selectively a first lyophilic region m the firstliquid-repellent region, forming a source electrode and a drainelectrode in the first lyophilic region of the base film by dropping acomposition including a conductive material; forming a semiconductorfilm over the source electrode and the drain electrode; forming a secondliquid-repellent region by a plasma treatment on the semiconductor film;forming selectively a second lyophilic region in the secondliquid-repellent region; forming a mask in the second lyophilic regionof the semiconductor film by dropping a composition including a materialof the mask; patterning the semiconductor film by using the mask;forming a gate insulating film to cover the semiconductor film; forminga third liquid-repellent region by performing a plasma treatment on thegate insulating film; forming selectively a third lyophilic region inthe third liquid-repellent region; and forming a gate electrode in thethird lyophilic region of the gate insulating film by dropping acomposition including a conductive material.
 21. The method formanufacturing a thin film transistor according to any one of claims 14to 20, wherein the liquid-repellent region is formed by forming a CF₂bond on the surface by the plasma treatment.
 22. The method formanufacturing a thin film transistor according to any one of claims 14to 20, comprising the steps of: forming an interlayer insulating filmover the thin film transistor; forming an opening portion in theinterlayer insulating film; forming a liquid-repellent region in asurface of the opening portion and the interlayer insulating film byperforming a plasma treatment on the interlayer insulating film in whichthe opening portion is formed; forming selectively a lyophilic region inthe opening portion of the liquid-repellent region; and forming a wiringto be connected to a source electrode or a drain electrode of the thinfilm transistor through the opening portion by dropping a compositionincluding a conductive material.
 23. The method for manufacturing a thinfilm transistor according to any one of claims 14 to 20, wherein theliquid-repellent region is irradiated with laser light to selectivelyform the lyophilic region.
 24. The method for manufacturing a thin filmtransistor according to any one of claims 14 to 20, wherein thecomposition is dropped by an ink-jetting method.
 25. A method formanufacturing a thin film transistor, comprising the steps of: forming afilm containing fluorine; forming selectively a lyophilic region in thefilm containing fluorine; forming a gate electrode on the lyophilicregion by dropping a composition including a conductive material; andperforming a heat treatment for baking the gate electrode, and removingthe film containing fluorine by the heat treatment.
 26. A method formanufacturing a thin film transistor comprising the steps of: forming afirst film containing fluorine; forming selectively a liquid-repellentregion in the first film containing fluorine; forming a gate electrodein the lyophilic region by dropping a composition including a conductivematerial; performing a heat treatment to bake the gate electrode, andremoving the first film containing fluorine by the heat treatment;forming a gate insulating film to cover the gate electrode; forming asemiconductor film over the gate electrode; forming a semiconductor filmhaving one conductivity over the semiconductor film; forming a secondfilm containing fluorine over the semiconductor film having oneconductivity and the gate insulating film; forming selectively a secondlyophilic region in the second film containing fluorine; forming asource electrode and a drain electrode in the second lyophilic region ofthe semiconductor film having one conductivity and the gate insulatingfilm by dropping a composition including a conductive material; andperforming a heat treatment to bake the source electrode and the drainelectrode, and removing the second film containing fluorine by the heattreatment.
 27. The method for manufacturing a thin film transistoraccording to claim 25 or 26, wherein a film including a Teflon or asilane coupling agent is formed as the film containing fluorine.
 28. Themethod for manufacturing a thin film transistor according to claims 25or 26, comprising the steps of: forming an interlayer insulating filmover the thin film transistor; forming an opening portion in theinterlayer insulating film; forming a liquid-repellent region in asurface of the opening portion and the interlayer insulating film byperforming a plasma treatment on the interlayer insulating film in whichthe opening portion is formed; forming selectively a lyophilic region inthe opening portion of the liquid-repellent region; and forming a wiringto be connected to a source electrode or a drain electrode of the thinfilm transistor through the opening portion by dropping a compositionincluding a material of the wiring.
 29. The method for manufacturing athin film transistor according to claims 25 or 26, wherein theliquid-repellent region is irradiated with laser light to selectivelyform the lyophilic region.
 30. The method for manufacturing a thin filmtransistor according to claims 25 to or 26, wherein the composition isdropped by an ink-jetting method.
 31. A droplet discharging method,comprising the steps of: forming a lyophilic region by irradiatingselectively on an object to be treated in which a liquid-repellentregion is formed with light by a light irradiation unit; and discharginga droplet onto the lyophilic region by a droplet discharging unit, in atreatment chamber including the droplet discharging unit and the lightirradiation unit.
 32. A droplet discharging method, using a treatmentapparatus in which a first treatment chamber having a plasma unit and adielectric, and a second treatment chamber having a droplet dischargingunit and a light irradiation unit, comprising the steps of: forming aliquid-repellent region in an object to be treated by the plasma unitand the dielectric in the first treatment chamber; transporting theobject to be treated into the second treatment chamber without beingexposed to the atmosphere; forming selectively a lyophilic region in theobject to be treated in which a liquid-repellent region is formed by thelight irradiation unit in the second treatment chamber; and discharginga droplet onto the lyophilic region by the droplet discharging unit. 33.The droplet discharging method according to claim 31 or 32, wherein thedroplet discharging unit and the light irradiation unit are integrallyformed.
 34. The droplet discharging method according to claims 31 or 32,wherein the light irradiation unit includes laser light.
 35. The dropletdischarging method according to claims 31 or 32, wherein the compositionis dropped by an ink-jetting method.